Encoding errors in Gmail?

[Kim Minh Kaplan]

Caleb Rogers writes:

> ERROR: UID 126179 
> (<ZF3lf1bGTw-Ct-Y9A15WlqUQ3BukrDdPHg-173.82.166.30 at ismtpd0003p1iad1.sendgrid.net>) 
[…]
> I also wasn't able to find the offending email on my gmail server 
> anywhere, at least not using gmail's search tools

Have you tried using the Rfc822msgid search operator?
https://support.google.com/mail/answer/7190

Kim Minh.