Greylisting begone

A few weeks ago I was in greylisting hell. Greylisting is used by mailservers to temporarily block (think 10min timeouts) emails coming from unknown servers. Thing is that all these OTP services nowadays use multiple mailservers, so your OTP code is stuck in greylisting hell because the service tries to send the mail again but from another new unknown mailserver, and again, and again...
In the end I just whitelisted the entire domain of that one service just to be able to logon, <rant>because passwords are so oldskool and OTP via email is all the rage nowadays</rant>. Today, while changing my emailadress on some sites, I once again bumped into greylisting timeouts. Cue me reading this blogpost and just straight up disabling greylisting. Let's see how this fares. For now, I'm happy with my instant OTP codes, though I still loathe them – albeit a bit less.

Disabling Greylisting on Mail-in-a-Box

Simply open the terminal and nano
sudo nano /etc/postgrey/whitelist_clients.local

Add:
/.*/

on its own line, save the file. 

Restart the service.
sudo systemctl restart postgrey

Rejoice.