2013-08-21 23:21 keltezéssel, Jan-Frode Myklebust írta:
On Wed, Aug 21, 2013 at 01:23:45PM +0200, Szládovics Péter wrote:
SOGo is not a mailserver. SOGo just an groupware extension for _any_
mailserver backend.
So, the question is not the antivirus and antispam for SOGo. The
question is antivirus and antispam for mailserver.
Antispam has a place in SOGo too. I'd like to have an interface for the
users to select how strict the spam-filter should be by integrating
with sieve-spamtest/rfc5235.
Maybe a "block sender" function, that pushes out a sieve script to the
server to drop/move-to-Spam messages from a given sender.
Also it would be nice if the SOGo webinterface had a Spam/not-spam
button that would move messages to/from the Spam-folder. This could be
used by http://wiki2.dovecot.org/Plugins/Antispam to train the filter.
Block senders?
How many senders need to block for correct spam filtering.
One node of one zombie network sends about 100 thousand spam emails per
day with randomly generated senders. Are you sure, you can stopped them
with this feature? I don't think so.
For correct filtering you need to use the followings in order of importance:
1. RBL checking with few reliable lists (ip and domain based too) - you
can eliminate the 90% percent of spams
2. Greylisting - you can eliminate the 90% of remain spams
3. virus filtering, attachment checking - you can eliminate phishing,
and trojean mails
4. content checking for spams (e.g. spamassassin) - you can eliminate
the almost all of remain spams
5. use sieve filters for sa spam marked headers (if you want)
Example.
My mail host gets about 250-300 clean, real mails per day (total
incoming mail traffic is about 2000 mails/day - yes, 80-90% of them are
absolutely spam).
The SA drops 5-10 mails into the quarantine per day (newsletters,
advertisements, badly formatted mail contents - really spams, very
rarely few false positive good mails).
All of others are back off to senders.
So, not perfect, cause usually one spam per week falls into my inbox.
Yes, not with only sieve filters.
The successful fight with spams there is at the gate, not at the mailbox.
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