New to PMG, please advice on user list!

[alexc]

Hello,

I try to set up PMG as a mail filtering system in front of my mail server (which is Exim+dovecot based). My Exim uses domain and user lists stored at Postgres (no LDAP), and I really wonder if PMG can get mail lists from Postgres (or via some kind of HTTP API requests) from my server?

What I imaging is this: I have say 100 mailboxes on my (Exim) mail server, and I expect PMG will accept messages only to or from these addresses, then process it, then pass to Exim. I don't want to maintain these lists separately on Exim/Postgres and on PMG as it may leads to mistakes, but still see no way to connect PMG to external database.

Surely LDAP would be the solution but can not afford to move to LDAP right away.

Looks like this is a common question, how other users of PMG deals with it?

Thank you!

 

[aaron]

The `Receiver Verification` works on the SMTP level.
If you enable it, the PMG will fake sending an email to the downstream mail server and if it does not return an error, that an email address does not exist, it knows that this is a valid account. The result is cached so it will not have to do the verification all the time.

 

[alexc]

The `Receiver Verification` works on the SMTP level.
If you enable it, the PMG will fake sending an email to the downstream mail server and if it does not return an error, that an email address does not exist, it knows that this is a valid account. The result is cached so it will not have to do the verification all the time.

Yes, looks like a solution. But what if my (Exim) server will temporarily be offline? The all these checks be failed, and the results will be cached.

But wait, if I'd have LDAP, it won't help in my question, it'll be the same 'Receiver Verification' only?

 

[aaron]

If the downstream server is offline and the account is not yet cached, the PMG will not get an error that an account does not exist but will run into a timeout. I am not 100% sure how it will react in this situation but probably it will return a 450 to the sending mail server, telling it to try the delivery at a later time.

But wait, if I'd have LDAP, it won't help in my question, it'll be the same 'Receiver Verification' only?

If you mean that the Receiver Verification will always use SMTP even if you have LDAP users configured then you are right.

LDAP can be used to log in to the quarantine interface and to build filter rules. See https://pmg.proxmox.com/pmg-docs/pmg-admin-guide.html#_ldap_integration