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  • Date: Tuesday, March 17, 2009 Time: 12:53 pm Category: Email, Groupwise Tagged attachments, Email, Groupwise, mime Discussion: 1 Comment

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If you are a GroupWise user, then you should continue reading this, because you could potentially reduce the size of your mail files – and those of any other GroupWise user you communicate with – by half.

How can a 587-byte image like this double the size of my email?

Here’s the scenario:  you’re sending a five megabyte attachment, like a PDF, to a group of coworkers.   However, one of the people on your distribution list is “outside” of our mail.wvu.edu system – they’re at hsc.wvu.edu, for example.  The entire body of your message merely says “See attached” and includes your GroupWise signature file, which serves as your electronic business card.  Being the proud Mountaineer, your signature even sports a little 587-byte “flying WV” logo.

You send your mail, but a few seconds later a message comes back from Mailer-Daemon informing you that your message is undeliverable – “Message size exceeds fixed limit.”

“Now wait a minute!” you say.  “The PDF attachment was only 5mb, and the file size limit is supposed to be 10mb.  What gives?”

Would you believe that the 587-byte graphic in the body of your message has caused your mail file to double in size?

Normally, GroupWise would have treated the tiny graphic in the body of your message as part of a rich text message.  However, as soon as GroupWise determined that one of your email recipients was outside of our mail system, it wrapped the entire message, attachment and all, into a MIME.822 “envelope” and added that to the overall email package.  It did this so that any unknown mail client on the internet would be able to make sense of your message.

The only way to prevent this from happening is to avoid putting a graphic (or any other binary) in the body of your message when you are sending to an outside user.

This is not just a cautionary tale about how to exceed a 10mb size limit with a 5mb attachment.  Think about it:  each time that you send an email with a MIME.822 attachment you are doubling the size of an item in your Sent Items folder.  You are also doubling the size of the email that everyone else on your distribution list receives from you!  Sometimes MIME can be a terrible waste.