ERROR: [5028-21-269-00000000] Exchange recipient limit reached: 204 limited to 100 (4348223)

When migrating mail with Migrator for GroupWise (MFG), the following error is logged:

ERROR: [5028-21-269-00000000] Exchange recipient limit reached: 204 limited to 100

The 204 and 100 in the above error can be various numbers.

By default, MFG is configured to limit the recipient list to 100 with the following default value:

[GroupWise]
MaxExpandedRecips=-1

The "-1" value is interpreted as "100" by MFG. In MFG 4.6.0.15 and later, this value will be increased to 500 by default.

The"MaxExpandedRecips" value can be altered based on your migration target:

For Office 365 migrations, the current limit (Sept 2016) is 500 recipients, which can be set in the gwmigapp.ini using the following parameter:

[GroupWise]
MaxExpandedRecips=500

For on-premise Exchange migrations, the "MaxExpandedRecips" limit in the MFG gwmigapp.ini needs to be set to reflect the Exchange transport settings that are configured in your Exchange environment. The following links are to Microsoft articles to help determine your current recipient limits in Exchange:

Exchange 2010:

https://technet.microsoft.com/en-us/library/bb676532(v=exchg.141).aspx

Exchange 2013 and 2016:

https://technet.microsoft.com/en-us/library/bb124345(v=exchg.160).aspx

If you are migrating a mail with a huge number of recipients, you could either increase this limit in Exchange or ignore this error. The recipient limit is set to prevent all users from performing huge mass-emails that could be considered as Spam.