occasional email gets retrieval stuck

Every now and then I see my getmail (cron) job get stuck retrieving from 
comcast.  It starts logging that the server "offered" an email (and the 
ID), but getmail could not retrieve it.  (Something to that effect.)  
Once one email does this, nothing else is retrieved, so one email stops 
getmail from getting anything further until I manually intervene.

In the past, I have had to start guessing and deleting emails from the 
source server (via their webapp) until the "offending email" is gone and 
then getmail is happy again.

Has anyone else seen this issue?

It would be great if I could correlate the IDs getmail is logging to the 
actual messages on the server and narrow-down the culprit. (IDK if it's 
strange headers or message size or encoding or what the issue is.)

It would be even better if getmail would just be able to retrieve the 
mail, of course.

Not sure why one email stops all functionality (actually deletes still 
happen - nothing can be retrieved).  The utility is typically very reliable.

Any ideas to troubleshoot or fix this issue?

getmail v5.16

Thanks,

AJ