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Email, Size limits on email

This page describes the size limits for campus email messages

The "total' message size limit for email messages include: the email header, attachments and message body.  

The limits are:  

Size Limit
Technical Notes
Exchange-to-Exchange100 MB
 Emails sent between 2 Exchange accounts using Exchange-native protocols, such as Outlook Web App and Outlook desktop client
Exchange ActiveSync
10 MB
Emails sent from mobile devices, such as iOS and Android devices, using Exchange ActiveSync
Campus relays
65 MB
 While email sent through the campus mail relays, such as Google Apps @ Illinois, Exchange mail accessed from an IMAP client, Express-SMTP, and can be as large as 65MB, the email may be rejected due to 3rd Party Email Provider limits. For example:
  • Gmail - 25MB
  • - 10MB
  • Yahoo - 25MB
  • AOL - 25MB
Campus mailing lists10 MB**Default setting. See Campus Mailing Lists, How to send attachments to a list for information on sharing documents.

In addition to total size limits, there are other limits per email:

  • Max attachment count = 256
  • Max file count in archive file = 256
  • Max directory depth in archive = 20
Email exceeding these limits are discarded. It is best to use a file sharing site like: for sharing large or complex files.


Keywordsemail, size limit, relays, Exchange, Google Apps, express-smtp, express, smtp, attachment   Doc ID57611
OwnerEmail Relays E.GroupUniversity of Illinois Technology Services
Created2015-10-20 09:32:54Updated2020-12-20 18:19:57
SitesUniversity of Illinois Technology Services
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