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The following table shows the most common combinations for the parameters that manage subscription status of imported recipients that are already present on MailUp

Action required on already existing recipientsConfirmEmailAsOptoutAsPendingForceOptIn 
No changes on subscription statusFalseFalseFalseFalseDefault case
Pending become Subscribed FalseFalseTrueFalseBad practice, please take care with itIt's a bad practice to force subscription of pending recipients at import time, the recommended
practice with double optin is that you import as pending and you let MailUp do this status change
when recipient actually clicks on the confirmation link.
Unsubscribed become SubscribedFalseFalseFalseTrueExcept for recipients that were unsubscribed due to hard bounce
or complaints feedback loop
Subscribed become PendingTrueFalseFalseFalseWith this configuration the confirmation email is sent to both
previously subscribed and previously pending
Unsubscribed become PendingTrueFalseAnyTrueExcept for recipients that were unsubscribed due to hard bounce
or complaints feedback loop
Despite of its name, "AsPending" value is ignored here.
Subscribed become UnsubscribedFalseTrueFalseFalse 
Pending become UnsubscribedFalseTrueTrueFalse 

titleBest practices
  1. Method call fails when another import process is running. You can use GetProcessDetails method to check if a previously started process is still running; while an alternative solution consist of periodically retry the method call until it returns


  2. Method response contains either a global ReturnCode or a specific ReturnCode for each import process that has been started by this method. Call is successful only when all ReturnCodes are equal to "0"

  3. There is not a known size limit for xmlDoc field: it has been successfully tested with 1.2 million characters (in this case return value is quite immediate but the whole import process could take several minutes and other import requests will be denied during this period)

  4. When using cloud services it can happen that your application must respect a size limit in API calls that is lower than the size of the XML that you would pass as xmlDoc parameter. In this case you can split your import data, call several times


    NewImportProcess with smaller recipient lists and then use StartImportProcesses (with empty xmlDoc parameter) to sequentially start all previously created import processes. This behavior requires MailUp 8.2.1 or higher. Please note that, when combining one or more calls to NewImportProcess and a final call to StartImportProcesses , the parameters of StartImportProcesses do not overwrite the import settings that were specified by each NewImportProcess request

  5. With ConfirmEmail=true, MailUp automatically selects the confirmation request message (you can customize it on Settings > List Settings > Notifications > Confirmation request) and it creates a queue of recipients that will receive that message. Please note that queue creation takes a while (even a couple of minutes if you have 1M recipients to be imported and notified) and queued message is made "ready for immediate sending" but it IS NOT automatically sent to the recipients. To send a queued message you can use StartDelivery method. You could also use  GetNewsletterQueues before calling StartDelivery in order to double check if queuing in "ImmediateSendingQueue" is completed.

Lists and Groups

You must specify either listIDs or listsGUIDs parameters. If you specify both fields, then the number of items in each parameter must match, and you must use semicolons to delineate empty values. We've provided examples below to help with understanding how to work with these parameters.