How to configure spam filter on Proxmox gateway

[LuckyA$$]

Hi Guys,

I've read many guide how to configure spam filter such as Body filter or Subject filter but i failed to test on my system, i did created a new Object in Mail Filter -> What Objects . But its doesn't work.

Could you guys give me a example how to modify Body filter.

Sorry for my bad english

Thanks.

 

[Stoiko Ivanov]

The MatchField entry should match case-insensitively - so the '(?i)' should not be necessary.
* a few of your regexes might match some false positives!
* the one with \n - won't work (I assume you try to match multiple headers) - the mail gets decomposed and each header is treated as its own field

As for the body filter - this works by creating custom spamassassin rules - check the pmg-admin-guide (section 4.8): https://www.proxmox.com/images/download/pmg/docs/pmg-admin-guide.pdf

however keep in mind that most of the simple sounding keyword filters might lead to quite some problems (e.g. https://en.wikipedia.org/wiki/Scunthorpe_problem)

Hope this helps!

 

[LuckyA$$]

It's work now . Thanks for your advice

 

[ithelpdesk]

The MatchField entry should match case-insensitively - so the '(?i)' should not be necessary.
* a few of your regexes might match some false positives!
* the one with \n - won't work (I assume you try to match multiple headers) - the mail gets decomposed and each header is treated as its own field

As for the body filter - this works by creating custom spamassassin rules - check the pmg-admin-guide (section 4.8): https://www.proxmox.com/images/download/pmg/docs/pmg-admin-guide.pdf

however keep in mind that most of the simple sounding keyword filters might lead to quite some problems (e.g. https://en.wikipedia.org/wiki/Scunthorpe_problem)

Hope this helps!

Dear Stoiko,

Is there any guidelines /official notes which help us to create these Spam keywords and Spam rules in detail..Because I see lot like this but not getting a good understanding to do my own.

Regards,
Liju

 

[Stoiko Ivanov]

Is there any guidelines /official notes which help us to create these Spam keywords and Spam rules in detail..Because I see lot like this but not getting a good understanding to do my own.

Not in our reference documentation, because we try not to encourage users to create their custom rules in general:
* most of the time bad detection rates are due to a misconfigured DNS setup (URIBL_BLOCKED results in the mail.log)
* using simple keywords leads to many false positives
* There are rather specific and rare cases where using a SA customization (more of reweighting the score of a rule than adding a new one ) can help for a while - and in these cases the requirements are quite tight and clear.

So put shortly - check your DNS setup and consider why mails are miscategorized first before considering to add your own custom rules.

Lastly to answer your question - the spamassassin docs have a description of creating custom rules: https://cwiki.apache.org/confluence/display/SPAMASSASSIN/WritingRules

 

[ithelpdesk]

Not in our reference documentation, because we try not to encourage users to create their custom rules in general:
* most of the time bad detection rates are due to a misconfigured DNS setup (URIBL_BLOCKED results in the mail.log)
* using simple keywords leads to many false positives
* There are rather specific and rare cases where using a SA customization (more of reweighting the score of a rule than adding a new one ) can help for a while - and in these cases the requirements are quite tight and clear.

So put shortly - check your DNS setup and consider why mails are miscategorized first before considering to add your own custom rules.

Lastly to answer your question - the spamassassin docs have a description of creating custom rules: https://cwiki.apache.org/confluence/display/SPAMASSASSIN/WritingRules

Thankyou Sir..

So in short We dont have to alter the spam filter settings unless we encounter some other problems other than due to DNS .

In my infrastructure most of our real clients sends email by addressing Dear.....XXX, But then Spam assaisn "Dear Something'' spam value will get triggered and adding 1. 7 score to it. How should I reduce it.? Which file I should update it with?

Regards,
Liju..

 

[Stoiko Ivanov]

In my infrastructure most of our real clients sends email by addressing Dear.....XXX, But then Spam assaisn "Dear Something'' spam value will get triggered and adding 1. 7 score to it. How should I reduce it.? Which file I should update it with?

Ok - this actually is one use-case where a modification might make sense! (However keep in mind that it is not unlikely that the receiving mail-server also might use SpamAssassin - and that the mail might get tagged on that end with the same result as on yours (more relevant if you use PMG as outbound relay))

@dcsapak is currently working on a feature to make this configurable via GUI (neither finished nor tested yet - so no timeline when it becomes available)

If you need it sooner you can add

score DEAR_SOMETHING X.Y

to '/etc/mail/spamassassin/custom.cf' to have the rule scored at X.Y (instead of 1.7)

run `spamassassin -D --lint` to check the syntax

and restart `pmg-smtp-filter` if everything looks good
(see also our reference documentation: https://pmg.proxmox.com/pmg-docs/pmg-admin-guide.html#_custom_spamassassin_configuration)

I hope this helps!

 

[ithelpdesk]

Ok - this actually is one use-case where a modification might make sense! (However keep in mind that it is not unlikely that the receiving mail-server also might use SpamAssassin - and that the mail might get tagged on that end with the same result as on yours (more relevant if you use PMG as outbound relay))

@dcsapak is currently working on a feature to make this configurable via GUI (neither finished nor tested yet - so no timeline when it becomes available)

If you need it sooner you can add

score DEAR_SOMETHING X.Y

to '/etc/mail/spamassassin/custom.cf' to have the rule scored at X.Y (instead of 1.7)

run `spamassassin -D --lint` to check the syntax

and restart `pmg-smtp-filter` if everything looks good
(see also our reference documentation: https://pmg.proxmox.com/pmg-docs/pmg-admin-guide.html#_custom_spamassassin_configuration)

I hope this helps!

Thankyou very much sir for your kind and detailed input on my question...I will try it and comeback..

Regards,
Liju