The following operations are supported. For a formal definition, please review the Service Description.

• AddExcludedAddress
  Use this method to add an excluded address at either a list, user or company level. For lists you should enter the mailinglistID. Otherwise this should be 0.
• AddUserToAccount
  Use this method to add a user to a customer account. Your login token must belong an account admin to use this method. You can specify whether or not you want the created user to also be an admin. Refer to Documentation for information on which fields are required. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. If you pass in an empty string for the password variable the method will create a password for you and return it to this variable.
• AddUserToAccountNonUK
  Use this method to add a user to a customer account. Your login token must belong an account admin to use this method. You can specify whether or not you want the created user to also be an admin. Refer to Documentation for information on which fields are required. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. If you pass in an empty string for the password variable the method will create a password for you and return it to this variable.
• AddUserToAccountNonUKPermissions
  Use this method to add a user to a customer account. Your login token must belong an account admin to use this method. You can specify whether or not you want the created user to also be an admin. Refer to Documentation for information on which fields are required. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. If you pass in an empty string for the password variable the method will create a password for you and return it to this variable.
• AddUserToAccountPermissions
  Use this method to add a user to a customer account. Your login token must belong an account admin to use this method. You can specify whether or not you want the created user to also be an admin. Refer to Documentation for information on which fields are required. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. If you pass in an empty string for the password variable the method will create a password for you and return it to this variable.
• AssignPriceBand
  Use this method to assign a price band to a customer. You must supply a valid GUID to use this method as well as a username associated with the customer account and the ID of the price band that you wish to apply. The customer and price band must be associated with your GUID. This method returns True if successful or False if a problem occured. The ReturnMessage provides details about the status or any problems that occurred.
• CalculateCostOfDataList
  Use this method to calculate the cost of purchasing a data list containing a given number of items.
• CalculateCostOfFindNearestMailing
  Use this method to calculate the cost of sending a letter (simple mailing), Mail Pack or postcard to a mailing list created from a find nearest request.
• CalculateCostOfMailing
  Use this method to calculate the cost of sending a letter (simple mailing), Mail Pack or postcard to a mailing list.
• CalculateCostOfSingleAddressMailing
  Use this method to calculate the cost of sending a letter (simple mailing), Mail Pack or postcard to a single address.
• CalculateEstimatedDeliveryDate
  Use this method to calculate the estimated delivery date of a letter based on the time passed in. This takes into account weekends, holidays and strikes. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). This method returns True if successful or False if a problem occured. The SendDateTime variable is the date and time when you wish to send letters out and the DeliveryDate is the estimated Royal Mail delivery date. The ReturnMessage provides an explanation of the estimated delivery date.
• CalculateEstimatedDeliveryDateNow
  Use this method to calculate the estimated delivery date of a letter based on the current time. This takes into account weekends, holidays and strikes. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). This method returns True if successful or False if a problem occured. The DeliveryDate is the estimated Royal Mail delivery date. The ReturnMessage provides an explanation of the estimated delivery date.
• CalculateLetterCostComplexBatch
  [Deprecated] Use this method to calculate a cost of a mail merge. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The method returns true on success and will also pass out the total Net Cost and VAT seperately.
• CalculateLetterCostComplexBatchWithExceptions
  [Deprecated] Use this method to calculate a cost of a complex batch (one containing letters with different numbers of pages) that requires validation exceptions. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). You must also create a MailBatch Object which stores the details about the letters being sent in the batch. The method returns true on success and will also pass out the total Net Cost and VAT seperately.
• CalculateLetterCostSimpleBatch
  [Deprecated] Use this method to calculate a cost of a simple batch(one contaning letters with the same number of pages) that does not require validation exceptions. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The method returns true on success and will also pass out the total Net Cost and VAT seperately.
• CalculateLetterCostSimpleBatchWithExceptions
  [Deprecated] Use this method to calculate a cost of a complex batch(one contaning letters with the same number of pages) that requires validation exceptions. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The method returns true on success and will also pass out the total Net Cost and VAT seperately.
• CalculateMailMergeCost
  [Deprecated] Use this method to perform a mail merge. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• CalculateSendDateForDeliveryDate
  Use this method to calculate the date on which you should send a letter for it to arrive on a specified date. This takes into account weekends, holidays and strikes. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). This method returns True if successful or False if a problem occured. The earliest and latest SendDate are the estimated send dates based on our batching and Royal Mail delivery. The ReturnMessage provides an explanation of the estimated delivery date.
• ChangePassword
  Use this method to change a user's password. You can only change the password of the user that you are logged into the API as.
• CreateAccount
  Use this method to create a customer account. The method also adds a user to the customer account who is specified as the account admin. Refer to Documentation for information on which fields are required. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. If you pass in an empty string for the password variable the method will create a password for you and return it to this variable.
• CreateAccountNonUK
  Use this method to create a customer account. The method also adds a user to the customer account who is specified as the account admin. Refer to Documentation for information on which fields are required. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. If you pass in an empty string for the password variable the method will create a password for you and return it to this variable.
• CreateAndSendMailPack
  Use this method to create and send a Mail Pack to a Mailing List. This will require a letterID from a previously uploaded letter, attachmentsID's and letterheadID are optional.
• CreateAndSendMailPackToFindNearest
  Use this method to create and send a Mail Pack to a Mailing list created from Find Nearest. This will require a letterID from a previously uploaded letter, attachmentsID's and letterheadID are optional.
• CreateAndSendMailPackToSingleAddress
  Use this method to create and send a Mail Pack to a Single Address. This will require a letterID from a previously uploaded letter, attachmentsID's and letterheadID are optional.
• CreateAndSendPostcard
  Use this method to create and send a postcard to a mailing list. An A5 landscape postcard in PDF format must be supplied with the mailing list ID.
• CreateAndSendPostcardToFindNearest
  Use this method to create and send a postcard to a mailing list created from a find nearest request. An A5 landscape postcard in PDF format must be supplied with the find nearest request details.
• CreateAndSendPostcardToSingleAddress
  Use this method to create and send a postcard to a single address. An A5 landscape postcard in PDF format must be supplied with the single address details.
• CreateAndSendSimpleMailing
  Use this method to create and send a Simple Mailing. A letter in either PDF or Word XML (.xml) must be supplied with a mailinglistID from a previously uploaded mailing list.
• CreateAndSendSimpleMailingToFindNearest
  Use this method to create and send a Simple Mailing to a Mailing list created from Find Nearest. A letter in either PDF or Word XML (.xml) must be supplied with addess details for the Find Nearest search.
• CreateAndSendSimpleMailingToSingleAddress
  Use this method to create and send a Simple Mailing to a single address. A letter in either PDF or Word XML (.xml) must be supplied with the single address details.
• CreateAttachment
  Use this method to upload a PDF attachment which can be attached to a letter when creating a Mail Pack. A number of attachments can be added to a Mail Pack. The attachmentID can be referenced for use with Mail Packs.
• CreateLetter
  Use this method to upload a new Letter in either PDF or Word XML (.xml) format. Letters can be used either in a Mail Pack or in a Simple Mailing. Document's uploaded in Word XML (.xml) format can contain Merge Fields which will be replaced when the Mailing is run. The letterID can be referenced for use with Mail Packs or Simple Mailings.
• CreateLetterhead
  Use this method to upload a new Letterhead in PDF format. Letterheads can be used in Mail Packs either on the first page or every page in the Pack. The letterheadID can be referenced for use with Mail Packs.
• CreateMailPack
  Use this method to Create a Mail Pack, a letterID must be supplied while both attachmentIDs and letterheadID are optional. A Mail Pack will be created which can then be sent to a single address or an address list.
• CreatePostcard
  Use this method to upload a new A5 landscape postcard in PDF format. A postcard can be defined by two pages in a single PDF or the first page of two PDFs.
• CreatePriceBand
  Use this method to create a new price band. You must supply a valid GUID to use this method as well as a unique description string to identify the price band. This method returns True if successful or False if a problem occured. It also provides the PriceBandID for your use. The ReturnMessage provides details about the status or any problems that occurred.
• DeleteAttachment
  Use this method to delete an attachment using it's unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The attachmentID you supply will be used to delete your attachment. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• DeleteExcludedAddressByID
  Use this method to get a delete an excluded address - you can get the ID by using the GetExcludedAddresses method
• DeleteLetter
  Use this method to delete a letter using it's unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The letterID you supply will be used to delete the letter. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• DeleteLetterByCustomerAPILetter
  Use this method to delete a letter. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken) and the letter specified by a CustomerAPILetter object must belong to you. This method returns True if successful or False if a problem occured. The ReturnMessage provides details about the status or any problems that occurred.
• DeleteLetterByLetterID
  [Deprecated] Use this method to delete a letter. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken) and the letter specified by an ID must belong to you. This method returns True if successful or False if a problem occured. The ReturnMessage provides details about the status or any problems that occurred.
• DeleteLetterhead
  Use this method to delete a letterhead using it's unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The letterheadID you supply will be used to delete your letterhead. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• DeleteMailPack
  Use this method to delete a Mail Pack using it's unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The mailPackID you supply will be used to delete your Mail Pack. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• DeleteMailingList
  Use this method to delete a mailing list using its unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The MailingListID you supply will be used to delete your mailing list. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure.
• DeleteMapping
  Use this method to delete a mapping using its unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The mappingID you supply will be used to delete your mapping. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure.
• DeletePostcard
  Use this method to delete a postcard using it's unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The postcardID you supply will be used to delete your postcard. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• DeletePriceBand
  Use this method to delete a price band. You must supply a valid GUID to use this method as well as the ID of the price band which you wish to delete. You can only delete a price band if no customers are currently using it. This method returns True if successful or False if a problem occured. The ReturnMessage provides details about the status or any problems that occurred.
• DeleteUserVariable
  Use this method to delete a user variable using it's unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The variableID you supply will be used to delete your user variable. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• DisableUser
  Use this method to disable a user account. You need to specify the username of the account that you wish to disable.
• DownloadDataList
  Use this method to download a specified data list as a CSV file. Note that not all data lists are permitted to be downloaded.
• FindNearestExecuteSearch
  Use this method to create a FindNearest List. The resulting list will contain all addresses within a radius or range surrounding the search address provided. This list can then be used when sending Simple Mailings or Mail Packs.
• FindNearestQueryAddress
  Use this method to query a FindNearest search. This method will not create a Find Nearest list but will return the cost of the list including how many addresses were found. Use the FindNearestExecuteSearch method to create a mailing list.
• GenerateMapping
  Generate an XML Mapping for a Mailing List.
• GenerateMappingWithDefaultName
  Generate an XML Mapping for a Mailing List and specify a default name.
• GenerateMappingWithDefaultNameAndMergeFields
  Generate an XML Mapping for a Mailing List and specify a default name and merge fields.
• GenerateMappingWithDefaultNameAndMergeFieldsWithID
  Generate an XML Mapping for a Mailing List and specify a default name and merge fields and get the ID.
• GenerateMappingWithDefaultNameWithID
  Generate an XML Mapping for a Mailing List and specify a default name and get the ID.
• GenerateMappingWithID
  Generate an XML Mapping for a Mailing List and get the ID.
• GetAccountUrl
  Gets a url to the users account page in the portal.
• GetBalance
  Use this method to retrieve your account balance. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). This method returns True if successful or False if a problem occured. Your account balance is returned in the AccountBalance parameter. The ReturnMessage provides an explanation in the event of a failure.
• GetCountries
  Use this method to get a list of all of the countries and their associated IDs. You need an ID to pass into the CreateAccount or AddUserToAccount methods if you wish to specify a non-UK address.
• GetDataListUrl
  Use this method to retrieve the URL of a specified data list.
• GetDataLists
  Use this method to retrieve a list of the user's data lists.
• GetDocumentation
  Use this method to retrieve a list of documentation urls such as the letter guidance template. A description and url is returned for each url.
• GetExcludedAddresses
  Use this method to get a list of your excluded address which are currently in use.
• GetLatestVersionDetails
  Gets the latest version of a specifed client application.
• GetLetterByID
  Use this method to retrieve a letter using it's unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The LetterID text you supply will be identify your letter. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. The returnLetter returns a CustomerAPILetter object.
• GetLetterStatusByCustomerAPILetter
  Use this method to check the status of a letter. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken) and the letter specified by a CustomerAPILetter object must belong to you. This method returns True if successful or False if a problem occured. The ReturnMessage provides details about the status or any problems that occurred.
• GetLetterStatusByLetterID
  Use this method to check the status of a letter. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken) and the letter specified by an ID must belong to you. This method returns True if successful or False if a problem occured. The ReturnMessage provides details about the status or any problems that occurred.
• GetLetters
  Use this method to retrieve a letter list. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The SearchDocumentName text you supply will be used to find your letter by its uploaded title. The SearchDocumentName can be a partial string, in which case the first matching letter is returned. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. The returnLetters returns an arrayList of CustomerAPILetter objects.
• GetLibraryAttachments
  Use this method to retrieve a list of the user's attachments that have been uploaded via the portal or the CreateAttachment API method.
• GetLibraryLetterheads
  Use this method to retrieve a list of the user's letterheads that have been uploaded via the portal or the CreateLetterhead API method.
• GetLibraryLetters
  Use this method to retrieve a list of the user's letters that have been uploaded via the portal or the CreateLetter API method. Letters uploaded via the UploadDocument or UploadConsolidatedPDF API methods are not supported.
• GetLibraryMailPacks
  Use this method to get a list of available MailPacks. An array of MailPack objects is returned with the newest MailPacks first.
• GetLibraryMappings
  Use this method to retrieve a list of the user's address list mappings that have been uploaded via the portal or the various GenerateMapping API methods.
• GetLibraryPostcards
  Use this method to retrieve a list of the user's postcards that have been uploaded via the portal or the CreatePostcard API method.
• GetMailHistoryDocumentsByJobId
  Use this method to retrieve a list of documents for a particular job. The method returns similar data to the page that is displayed within the Portal when you click on a particular job and it lists the documents.
• GetMailHistoryJobs
  Use this method to retrieve a list of jobs. The method returns similar data to the Mail History page within the Portal.
• GetMailPacks
  [Deprecated] Use this method to get a list of available MailPacks. The list is returned as a pipe-delimited string with the newest MailPacks first.
• GetMailingListByID
  Use this method to retrieve a mailing list using its unique ID. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The MailingListID you supply will be used to locate your mailing list. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. The returnMailinglist returns a CustomerAPIMailingList object.
• GetMailingLists
  Use this method to retrieve a list of mailing lists. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The SearchMailingListTitle text you supply will be used to find your mailing list by its uploaded title. The SearchMailingListTitle can be a partial string, in which case the first matching mailing list is returned. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. The returnMailinglists returns an ArrayList of CustomerAPIMailingList objects.
• GetMessage
  Get the return message.
• GetPortalUrl
  Gets a url to the specified portal page.
• GetPriceBands
  Use this method to return a delimited string containing the details of all price bands associated with your GUID. You must supply a valid GUID to use this method. This method returns True if successful or False if a problem occured. The ReturnMessage provides details about the status or any problems that occurred.
• GetUserDetails
  Use this method to get Baisc User Deta, User Pricing and VatRate.
• GetUserVariables
  This method returns a list of variables, similar to the functionality of the Merge Fields page within the Portal. The variable name and value are returned.
• IsValidLoginToken
  Checks whether the supplied login token is valid or not.
• MailMerge
  Use this method to perform a mail merge. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The Letter and MailingList you supply will be used to select the letter template and mailing list to be used. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• MailMergeWithExceptions
  Use this method to perform a mail merge. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The Letter and MailingList you supply will be used to select the letter template and mailing list to be used. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• MailMergeWithExceptionsAndConfirmationEmails
  Use this method to perform a mail merge. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The Letter and MailingList you supply will be used to select the letter template and mailing list to be used. You can choose whether you want to send a confirmation email out for each letter. This method returns True if successful or False if a problem occurred. The ReturnMessage provides an explanation in the event of a failure.
• PreviewDocumentFindNearest
  Gets a byte array that represents the finalized document to be sent to a mailing list created from a find nearest request.
• PreviewDocumentMailingList
  Gets a byte array that represents the finalized document to be sent to a mailing list.
• PreviewDocumentSingleAddress
  Gets a byte array that represents the finalized document to be sent to a single address.
• PreviewLetter
  [Deprecated] Gets a byte array that is the PDF letter with the stickered address. Only works for addresses with a valid postcode.
• PreviewLibraryAttachment
  Gets a byte array that is the attachment which was uploaded via the portal or the CreateAttachment API method.
• PreviewLibraryLetter
  Gets a byte array that is the letter which was uploaded via the portal or the CreateLetter API method. Letters uploaded via the UploadDocument or UploadConsolidatedPDF API methods are not supported.
• PreviewLibraryLetterhead
  Gets a byte array that is the letterhead which was uploaded via the portal or the CreateLetterhead API method.
• PreviewLibraryPostcard
  Gets a byte array that is the postcard which was uploaded via the portal or the CreatePostcard API method.
• PreviewMailPack
  Gets a byte array that is the PDF Mail Pack with the stickered address. Only works for addresses with a valid postcode.
• RetryLetter
  Retry sending a letter which couldn't previously be sent.
• SearchAddress
  Passed an address to search for in InputAddress (can be partially complete), returns a list of postal addresses as well as descriptive text (ReturnMessage) and a code (PafCode) for the results of the search. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). If an address search fails the PafCode and ReturnMessage parameters will have more detail and the list of returned addresses will be empty.
• SendLetter
  [Deprecated] Use this method to send a letter. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure.
• SendLetterWithStructuredAddress
  [Deprecated] Use this method to send a letter using a structured address block (as returned by SearchAddress) and receive detailed information on the address validation if it fails (PafCode and ReturnMessage). You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure.
• SendLetterWithStructuredAddressAndExceptions
  [Deprecated] This method is a specialisation of the old SendLetterWithStructuredAddress that allows users force an address i.e. it is not checked against the PAF database. There is additional cost for this option.
• SendMailPack
  Use this method to send a previously saved Mail Pack.
• SendMailPackToFindNearest
  Use this method to send a previously saved Mail Pack to a Mailing list created from Find Nearest.
• SendMailPackToSingleAddress
  Use this method to send a Mail Pack a previously saved MailPack to a Single Address. This will require a Mail Pack ID and single address details.
• SendMailPackToSingleAddress2
  Use this method to send a Mail Pack a previously saved MailPack to a Single Address. This will require a Mail Pack ID and single address details. This method is used by the ViaPost Spooler software. SendMailPackToSingleAddress should be used for any API integration.
• SendPostcard
  Use this method to send an existing postcard to a mailing list.
• SendPostcardToFindNearest
  Use this method to send an existing postcard to a mailing list created from a find nearest request.
• SendPostcardToSingleAddress
  Use this method to send an existing postcard to a single address.
• SendSimpleMailing
  Use this method to send a Simple Mailing. A simple mailing consists of a previosly uploaded letter and an address list.
• SendSimpleMailingToFindNearest
  Use this method to send a Simple Mailing to a Mailing list created from Find Nearest. A simple mailing consists of a previosly uploaded letter and address details for a Find Nearest search.
• SendSimpleMailingToSingleAddress
  Use this method to create and send a Simple Mailing to a Single Address. A letter in either PDF or Word XML (.xml) must be supplied with the single address details.
• SignIn
  Use this method to sign in to the ViaPost User Webservices. Signing in is mandatory and must be done before any other service methods can be used. You must supply a valid Viapost Username and Password. Returns a LoginToken which must be supplied as a parameter to the other methods. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure.
• UpdateLetter
  Use this method to edit an existing letter. The new ID will be returned and all references to the letter will be updated.
• UpdateMailPackLetter
  Use this method to update a Mail Pack to refer to a different letter.
• UploadConsolidatedPDF
  [Deprecated] Use this method upload a Consolidated PDF. The consolidated PDF will be splint into individual documents based on SplitOptions and then sent/uploaded as individual letters.
• UploadDocument
  [Deprecated] Use this method to upload a PDF document. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The Letter Name you supply will be used to display your letter. The DocumentData parameter must contain your PDF as a Base64-encoded byte array. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. The LetterID is populated with the new record ID once the letter has been uploaded.
• UploadMailingList
  Use this method to upload a mailing list in CSV format (refer to the CustomerAPI documentation for details on the CSV format requirements). You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The Mailing Address Name you supply will be used to display your mailing list. The MailingListData parameter must contain your CSV data as a Base64-encoded byte array. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. The MailingListID parameter is populated with the ID of the new record.
• UploadMailingListWithMapping
  Use this method to upload a mailing list in CSV format. You can also specify the ID of a custom mapping to successfully extract the addresses from your spreadsheet. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The Mailing Address Name you supply will be used to display your mailing list. The MailingListData parameter must contain your CSV data as a Base64-encoded byte array. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. The MailingListID parameter is populated with the ID of the new record.
• UploadMailingListWithMappingAndShare
  Use this method to upload a mailing list in CSV format. You can also specify the ID of a custom mapping to successfully extract the addresses from your spreadsheet. You must supply a valid LoginToken to use this method (use SignIn to acquire a LoginToken). The Mailing Address Name you supply will be used to display your mailing list. The MailingListData parameter must contain your CSV data as a Base64-encoded byte array. This method returns True if successful or False if a problem occured. The ReturnMessage provides an explanation in the event of a failure. The MailingListID parameter is populated with the ID of the new record.