Maybe it should be removed in future VM releases?
We probably need to switch to some other policy server type thing. rspamd has come up in the past as a possibility, as it supports most, maybe all, of the stuff we use various milters for. But, thatāll require quite a bit of work and some incompatible changes.
Greylisting can be a pain as there so many verification codes needed now from companies.
Iām not surprised there are problems.
Grey listing is not about codes, it is about real email servers retrying later.
Entering codes is a different system.
Bring it on 
A email verification should take a less then a minutes, greylisting delays the process.
I am not saying the code system does not have its place, just that it was not grey listing.
Rwpamd has lots of plugins a d it might have this as a feature. I donāt think virtualmin has this at the moment anyway, of does it?
I didnāt say it was about codes, I said it makes it a pain, Iāve had customer complain why there verification code hasnāt arrived to there inbox.
ooh you mean like one time passcodes for logging into their 3rd party accounts. 
I thought you were on about where someone send and email to an email server, that server then sends an email and they have to validate they are a real person before their emails are allow through.