Great news effective now we announced that we have upped the attachment migration limit size to 150MB attachments. This migration attachment limit was previously 25MB which caused a lot of attachment mitigation prior to migration if your on prem quota was larger than 25MB. This is an excellent bump in migration attachment size to help avoid attachment mitigation!
This new limit will apply to Exchange migrations as well as IMAP migrations, and other email platforms, etc. If you also note above – the send/receive attachment limit remains at 25-36MB depending on the client. The good news however is if you look on the Office 365 Roadmap under ‘In Development’ here you will see there are future plans to make the send/receive attachment limit the same quota of 150MB which is also great news!
Please see the announcement here
Public service description update here