Office 365 Message / Attachment Size Limit

Modified on Mon, 23 Mar at 3:57 PM

Connect to Exchange Online:

Connect-ExchangeOnline

Get list of mailboxes and their size limits:

Get-Mailbox -ResultSize Unlimited | Select-Object DisplayName, UserPrincipalName, MaxSendSize, MaxReceiveSize | Out-GridView

Get organization wide limits:

Get-TransportConfig | Select-Object MaxSendSize, MaxReceiveSize

Get defaults for new mailboxes:

Get-MailboxPlan | Select-Object Name, MaxSendSize, MaxReceiveSize

Update all mailboxes to the maximum size:

Get-Mailbox -ResultSize Unlimited | Set-Mailbox -MaxSendSize 150MB -MaxReceiveSize 150MB

Update all mailbox plans to the maximum size:

Get-MailboxPlan | Set-MailboxPlan -MaxSendSize 150MB -MaxReceiveSize 150MB