A client called today because their email wasn't arriving at the receipants inbox but bouncing back with a 'poor MTA rating' error.

Checked about every blacklist I know and our server was definitely not blacklisted. Must be the receipants host which for some reason was blacklisting his specific email address.

Told the client that it wasn't a problem on our side and that he had to request a whitelist himself (we'd do it but it wasn't a specific server problem so we're not going to spend time on that).

Fair enough, he'd do that.

Calls back. "Well, the other party says that your server definitely has a poor rating, it's on your side!!"

Alright, this is getting annoying. Gave him a few blacklist checking sites links and told him to run his domain AND our server IP through it. Indeed came back completely clean.

"But the other party said it's poor rating on your side so I'd think tha........"

YEAH WHY DON'T YOU SHOVE THAT OTHER PARTY UP YOUR FUCKING ASS. I'VE SHOWN YOU PROOF THAT IT'S DEFINITELY NOT ON OUR FUCKING SIDE, EXPLAINED IT TO YOU AND SO ON. MAYBE, FOR ONE FUCKING SECOND, TAKE INTO CONSIDERATION THAT THE OTHER PARTY IS FUCKING LYING?!?!?

FUCK OFF.