ITS Online»Email, Calendar & MS Office

Email Attachments

When sending email with attachments through Office 365, there are some limitations for file size and type. If you have any questions, please contact 

Message Size

The maximum size of a message, including all attachments, that you can send in Office 365 is 25 megabytes. 

Blocked Files

Outlook allows you to send any kind of attachment (up to the 25 MB per message limit), but blocks some incoming attachment types, specifically those types that could carry a virus or other malware. See a list of blocked file types (PennKey required).


If someone sends an email larger than 25 MB or a blocked attachment type to a Penn Carey Law mailbox, they will receive an automatic non-delivery email message stating that the email couldn’t be delivered.


If you want to share a file larger than 25 MB or a blocked file type, we recommend:

1. OneDrive is the most flexible option for filesharing. You can share with people at Penn Carey Law and external to the law school. Check out this link for details on how to share files with OneDrive.

2. SharePoint is recommended for file collaboration within law school departments or centers.

3. Penn + Box ( is another flexible option for sharing files. 

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