Troubleshooting Mail.app: Choking on large messages?

Our investigation into Comcast mail retrieval issues (caused in some cases by problematic messages on the server that can be deleted through the Web interface) also led us to a potential problem with Mail.app when encountering certain types of large messages:

MacFixIt reader Geoff Wysham writes "Some time ago (not long after moving to Mac OS X) I had problems with Mail.app crashing whenever trying to download mail off of my ISP's server (GMPExpress in Southern Maryland). Investigating through their Web interface, I found a message of over 14.5 MB. After doing some investigation, it appeared someone had mistakenly sent their entire Inbox as a message to one of the lists I was on, and Mail was choking on it. Deleting that 1 message allowed me to download the remainder of my mail through Mail in the normal fashion."

So it appears that there may be some messages that cannot be properly interpreted by Mail.app when using a POP account. If you think you might be affected by this issue, try logging into the Web interface for e-mail access (most Internet service providers offer this service) and check for mail that you have not received in your regular client.

In many cases, deleting the offending message will allow e-mail to properly flow into Mail.app and other clients.

Other readers report that rebuilding the Mail.app database (go to Mailbox > Rebuild) after deleting mail messages from the server was required for new mail to appear properly.

Feedback? Late-breakers@macfixit.com.

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