Update 4/15/15 – Office 365 has increased the allowed maximum message size to 150 MB, giving Office 365 administrators the ability to set the maximum message size of their choosing from 1 MB up to 150 MB. The default maximum message size for Office 365 mailboxes is still 25 MB, and they don’t plan on to changing the setting on existing accounts.
More at https://blogs.office.com/2015/04/15/office-365-now-supports-larger-email-messages-up-to-150-mb/
I’m currently on project finishing an Office 365 migration (yay – I’m finally back together with my true love: messaging!) and we’re in the process of migrating their 50+ domains off of FOPE, as they were initially a Wave 14 tenant, and over to EOP. Technically, they were automatically migrated to EOP as part of the upgrades in Q3/Q4 2013, however they still have their MX records pointing to either the mail.messaging.microsoft.com or mail.global.frontbridge.com domains, so traffic is being first routed thru FOPE before it makes it to EOP. And if you may or may not know, it’s crunch time and Microsoft wants everyone off by June 1 (if you have an O365 domain):
As part of determining the impact these MX record changes will have on message flow, the big one is around accepted message size. In FOPE, if a message went over the size limit you could have it qurantined and the messaging administrator could release it to the mailbox, granted your Receive Connector allowed it, and your MaxReceiveSize on your mailbox matched according.
A large debate has come up around Exchange Online limits, as detailed below:
In talking with my collegues, there was a lot of confusion around message limits, and in talking with with my contacts in Microsoft, I can finally clear the air on what these limits are. And it’s actually simpler than you think Continue reading “Exchange Online message limits – not that cut and dry!” »