Only using Quest Migration Manager for Active Directory (QMMAD) and need Exchange attributes migrated as well for Office 365 migrations? Normally this would not be possible without contacting Quest and having them supply a custom XML file or using Quest Migration Manager for Exchange (QMMEX). Recently Quest has added a XML to QMMAD that will migrate needed attributes for Office 365 migrations. The file is SyncExchangeRelatedAttributes.xml and is located in the directory C:\Program Files (x86)\Quest Software\Migration Manager\Active Directory on the server QMMAD is installed. In order to migrate mail attributes when using the Migration Wizard you must select the file during the initial migration session. The migration session can create new objects in the target domain or merge onto an existing object. During the migration session on the Object Processing tab you select the xml file. Attributes that are synchronized using the out of the box .xml file are mail, targetaddress, proxyaddress and legacyExchangeDN. Since this is an XML file additional attributes can be included by modifying the file. I have attached the file for your review.
In addition if you want to migrate/merge users without any attributes then a separate .xml file can be used called skippall_attr.xml. Both files are available for download on a separate yammer post. Have fun and migrate on!