[SOLVED] Reject SPAM

[s0undt3ch]

I'm a new user to zimbra and I'm just questioning some of its configurations and way to work. I'll explain.

On my previous mail server install(Qmail/vPopmail) i was able to, while receiving a message, reject if it's know spam, scored way above the allowed score by spamassassin for example.

Although I'm not seeing any spam way higher than allowed max score on mu Junk folder, I do see bounce on the logs.

Wouldn't it be better, or is it even possible to reject to receive the message if it's know spam?

Personaly I feel that bouncing spam is good for spam since most accounts are bogus or stolen, hence, my question to reject, and if possible let them know why it is rejected, "Know SPAM, Rejecting".

Regards,
Pedro Algarvio

[phoenix]

Bouncing (almost) any email doesn't solve the problem, it just causes extra and mostly unnecessary traffic. Don't forget if the mail address is bogus you'll just end up bouncing the message between servers until it's finally dropped. One form of spam attack is to 'bounce' messages so they end up in a particular mailbox. You can achieve a much better result by rejecting unknown recipients.

Spamassassin determines if the message is spam and uses that to train it's filters, depending on the spam kill/tag percentages you should see very little spam in your inbox.

[s0undt3ch]

Originally Posted by phoenix

Bouncing (almost) any email doesn't solve the problem, it just causes extra and mostly unnecessary traffic. Don't forget if the mail address is bogus you'll just end up bouncing the message between servers until it's finally dropped. One form of spam attack is to 'bounce' messages so they end up in a particular mailbox. You can achieve a much better result by rejecting unknown recipients.

Spamassassin determines if the message is spam and uses that to train it's filters, depending on the spam kill/tag percentages you should see very little spam in your inbox.

My idea is not to bounce, it's to reject while receiving it, because if my smtp accepts the message it can't just drop it, it must deliver it.

[s0undt3ch]

Originally Posted by s0undt3ch

My idea is not to bounce, it's to reject while receiving it, because if my smtp accepts the message it can't just drop it, it must deliver it.

Hmm, I guess this is what RBL's are for.

And probably the only way?

[phoenix]

Your original post sounded like you wanted to bounce. My personal opinion is that RBLs are mostly a waste of time as well, too many non-spammers get on there. I don't use them and never have, I see zero spam in my inbox and a few in my Junk folder (there's about 10 in there on average).

Just reject mail for unknown users, change the kill/tag percentages and you'll see a dramatic reduction in spam going through the system.

[s0undt3ch]

Originally Posted by phoenix

Your original post sounded like you wanted to bounce.

No, never bounce, I'd actually like to stop zimbra from bouncing it.

Originally Posted by phoenix

My personal opinion is that RBLs are mostly a waste of time as well, too many non-spammers get on there.

I only ever ran a home server, never got any false positives from them.

Originally Posted by phoenix

I don't use them and never have, I see zero spam in my inbox and a few in my Junk folder (there's about 10 in there on average).

Just reject mail for unknown users, change the kill/tag percentages and you'll see a dramatic reduction in spam going through the system.

Doesn't zimbra reject for unkown users by default?

[fajarpri]

I enable 'smtpd_reject_unlisted_recipient = yes' in main.cf, but when I test it by sending to a non-existence email from zimbra webmail, it got through, although a moment later I received bounce message.

Is it the intended behaviour? Can we make the connection to be "rejected" in smtp level just like qmail does?

[Klug]

You should modify /opt/zimbra/conf/zmmta.cf and not main.cf (that is updated each 30 minutes by Zimbra).

[phoenix]

Originally Posted by fajarpri

I enable 'smtpd_reject_unlisted_recipient = yes' in main.cf, but when I test it by sending to a non-existence email from zimbra webmail, it got through, although a moment later I received bounce message.

You've modified the wrong file, use the one that Klug mentioned. and is also in several thread in the forum.

Originally Posted by fajarpri

Is it the intended behaviour? Can we make the connection to be "rejected" in smtp level just like qmail does?

That is what you're doing with this modification. You will also need to make this change after every upgrade as this modification doesn't persist.

You should also have started a new thread for this rather than tag it on the end of a thread about RBLs.

[fajarpri]

Thanks @klug, @phoenix.
I'll try searching the forum again with POSTCONF smtpd_reject_unlisted_recipient no keyword.

I'll start a new thread when issue arises.