Maximum size for email messages at IU
At Indiana University, the limit on all outgoing or incoming email messages is 20 MB. Messages larger than this will not go through IU email systems, and attempting to send such messages will result in either an error message from your email client or a non-delivery notice from IU. This size limit includes the message itself and any attachments associated with it.
If you're using IU Webmail to access your Cyrus account, the maximum file size for an individual attachment is 2 MB; for multiple attachments, the total limit is 14 MB per email. This restriction results from the way Webmail encodes attachments, which can substantially expand their size. Restricting the size of your attachment to 14 MB makes it likely that it and the message will fall under the 20 MB limit. However, even if Webmail accepts an attached file, the file may be rejected at the relays for exceeding the size limit.
Note: The 14 MB limit applies to attachments being sent from Webmail; the Webmail client can view larger attachments you receive.
The 20 MB limit reflects the size supported by IU's email environment; most organizations outside of IU will reject messages above 8-10 MB. Therefore, when sending email messages to non-IU addresses, you may have to further reduce your message size.
To reduce the size of outgoing email, consider the following options:
- Large or multiple attached files are the main reason that email
messages exceed the maximum size limit. Though unlikely, it is also
possible that the text of the message is too large. Remove
attachments or edit the message until it is less than the maximum size.
Alternatively, break it into several smaller files that individually
do not exceed the limit.
- Use a file compression utility to compress your large attachment into a smaller file size. Some compression utilities can also divide one large file into several smaller files that you can then send separately. Both Windows and Mac operating systems have built-in compression software. For assistance with the built-in utility for Windows see In Windows, how do I compress or decompress files?; or for Mac, see In Mac OS X, how do I compress or decompress files? Third party compression utilitys exist too (some free, some not) and include 7-Zip for Windows, and DropStuff and StuffIt Deluxe for Macintosh.
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Graduate students, faculty, and staff can use the Slashtmp service to temporarily store and share large files via a web interface.
- Rather than sending a large attachment over email, put it on a
web page and give your recipient the URL for the
file.
- Use a third-party freeware or shareware file
transfer or chat program to transfer the file to your recipient. These
are widely available through software download sites on the
web.
- If your recipient has a network drop box, see if you can place
your file there. There are a variety of methods to create a drop box,
including anonymous FTP, Mac and Windows file sharing, and
Oncourse.
- If both you and your recipient have accounts on the same Unix
computer system, you can temporarily set the file permissions so that
your recipient can access and copy it. For information about changing
file permissions, see In Unix, how do I change the permissions for a file?
- Removable storage devices, such as recordable CDs and DVDS, flash drives, or SuperDisks, can hold a large amount of information. For very large files, the most practical way of transferring information might be to copy the files to such media, and hand deliver or ship the media to your recipient.
