Introduction #
By default, Exchange Online has a send and receive limit of 35 MB for messages, this can be increased to 150 MB.
The message size includes both the message body and attachments.
We recommend you increase the maximum message size for sent and received messages to 150 MB.
This setting should be set in conjunction with Set Maximum Message Size – Setting for Existing Mailboxes
NOTE: Setting the message size for Group Mailboxes is not support by Microsoft.
License Requirement #
Any Exchange Online plan
User Impact #
Low
Any new mailboxes created (except Group Mailboxes), will have a maximum message send and receive size set to the parameter in MSPMagic.
*This setting cannot apply to Group Mailboxes as Microsoft Exchange Online does not support this. MSPMagic will also ignore the Discovery Mailbox in all tenants.
Admin Portal Reference #
- login to Exchange Online admin center as the Global Admin
- Click on reciepients -> mailboxes
- Click on the elipsis “…” and -> Set default message size restrictions

4. On the pop up windows set your Maximum Message Send and Recieve size. Click OK to apply.

PowerShell Reference #
MSPMagic modifies this setting via PowerShell. The following cmdlets are run on the tenant’s Exchange Online.
Get-MailboxPlan | Set-MailboxPlan –MaxSendSize <$MaxSendSize> –MaxReceiveSize <$MaxReceiveSize>
If Action is set to Notify #
We report the setting is compliant if all MailboxPlan’s (each Exchange Online SKU has it’s own plan) MaxSendSize and MaxRecieveSize match the parameters set in MSPMagic.
We report the setting is non-compliant if any of the MailboxPlan’s (each Exchange Online SKU has it’s own plan) MaxSendSize and MaxRecieveSize do not match the parameters set in MSPMagic.
If Action is set to Enforce #
We report the setting is compliant if all MailboxPlan’s (each Exchange Online SKU has it’s own plan) MaxSendSize and MaxRecieveSize match the parameters set in MSPMagic.
We report the setting is compliant-fixed if MSPMagic had to modify the MaxSendSize and MaxRecieveSize of any of MailboxPlans to match the parameters set in MSPMagic.