Increase Mail Attachment Size in Office 365 Exchange Online

|   20-Jun-18

The default Office 365 maximum message size for messages is 25MB. Since email text is usually shorter, this setting essentially restricts maximum attachment size. You can change the maximum message size for an individual mailbox with Office 365 Admin Center or PowerShell. Here I have discussed two methods of how to increase mail attachment size in Office 365 exchange online, you can use any one of them.

Method 1: How to set Office 365 attachment size limit using a console

Step 1: First login your Office 365 admin account >> Admin >>Admin Center >> Exchange


Step2: Now you will see that admin center window will open on the screen >>recipients>> mailbox then go to “…” sign and click on Set default message size restriction option.

exchange admin center

Step 3: When you click a new pop up will appear on the screen, here you need to type the size in KB. And hit Ok

default size restrictions

Note: you can also customize multiple mailboxes by the same process after that select the multiple user’s mailboxes>> Bulk Edit pane under Message Size Restrictions>>Update.

multiple users

Note: you can customize a single user mailbox by the another way

Admin Center>> recipients>> mailboxes, here you need to select a user’s mailbox. Then click on the edit icon>> message Size Restrictions>> click view details and specify the maximum message size.

Method 2: set recipient limit office 365 PowerShell

If you have less than 1,000 or more than 1,000 users mailboxes, then you will eventually end up using the Exchange Admin Center User Interface to make changes and also use the PowerShell command.

Step 1: First, you need to login Office 365 with the help of PowerShell

$Cred = Get-Credential

Step 2: Press the enter key and type your office 365 username and password and then type the following commands.

$Session=New-PSSession –ConfigurationName Microsoft.Exchange –ConnectionUri -Credential $Cred –Authentication Basic –AllowRedirection

Import-PSSession $Session

Step 3: The general commands you can use to customize these settings via remote powerplays include:

Update a single mailbox

Set-Mailbox –Identity –MaxSendSize 75MB – MaxReceiveSize 75MB

  • Update multiple mailboxes

(“sale”,”sale2”,”sale3”)|%{Set-Mailbox –Identity $_-MaxSendSize 75MB-MaxReceiveSize 75}

  • Update all mailboxes

Get-Mailbox | Set-Mailbox –MaxSendSize 75 MB –MaxReceiveSize 75 MB

  • Update the default settings

To create for the mailbox in the future.

Get-MailboxPlan | Set-MailboxPlan –MaxSendSize 75MB –MaxReceiveSize 75MB

Conclusion :

In this article, I explained how to increase mail attachment size in Office 365 and discuss two methods, one is console and another is PowerShell. Use any one of them which is comfortable for you. If you have still any doubts then leave a message in the comment box.

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