[pkg-fetchmail-maint] Bug#676268: SMTP 553 5.1.3 "invalid route address" error after MAIL FROM causes failure of fetching

[Trevor Cordes]

Package: fetchmail
Version: 6.3.21

A remote POP3 server has some emails we want to fetch with bad FROM 
addresses, it would appear.  This causes fetchamil to quit that fetch and 
the mail piles up in that POP3 box and end users think they are not 
getting any email.  On each subsequent fetchmail run it tries to get the 
same bogus message and dies at the same place.  It never gets past it.

fetchmail: SMTP> MAIL FROM:<DE@@email.bigpublications.ca> BODY=8BITMIME SIZE=15587
fetchmail: SMTP< 553 5.1.3 <DE@@email.bigpublications.ca>... Invalid route address
fetchmail: SMTP> RSET
fetchmail: SMTP< 250 2.0.0 Reset state
........fetchmail: socket error while fetching from hidden at remote.hide.me

At the MAIL FROM stage, the fetchmail source appears to ignore any 
antispam directives (like "antispam 553").  Errors at this stage are not 
handled well.

Fetchmail should look at the antispam codes at this stage also, and react 
accordingly.  In this case I would want it to drop this email and keep 
going with the fetch.  Alternatively, fetchmail could look at the FROM and 
fix it, though that may be a bad idea for many reasons.

The config line in question looks like:

poll remote.hide.me with proto POP3 auth password
    user 'bob' there with password 'pw' is 'bob'  here options 
    fetchall stripcr mimedecode fetchlimit 15 antispam 553

Also tried with many variations for antispam, and fetchlimit 1 for 
debugging/testing.