|
[Date Prev][Date Next]
[Chronological]
[Thread]
[Top]
[NMLUG] Email service that does graylisting/razor/spamfiltering/etc?
I just wanted to add my two cents. Greylisting works only marginally
now, at least from what I see on the linux smtp gateway I run. Most
spammers are actually resending. In this case your only hope is to delay
the message long enough with greylisting to have a RBL list it.
Greylisting will highlight a mis-configured mail servers that send to
you, some do not resend. Do not accept the default message delay time
(300secs) spammers have taken this into account. So not advertise in the
450 message the time you are using, spammers are looking for this and
will adjust accordingly.
I would recommend against sending bounces. Bouncing spam and/or viruses
contributes to the joe-job problem, wastes bandwidth on delivery failure
messages that will never reach a valid recipient and generally irritates
people who receive the bounce but never sent a message. Don?t do it. By
the time you?ve processed a peice of mail and determined that it?s
either spam or a virus, you?ve determined that it?s either spam or a
virus. Why would you then send that garbage on?
Also to get a smtp gateway or spamassassin/mail filtering running
smoothly it takes time to train it so it requires patients. You will get
false positives.
One of the best things that I've started doing on smtp gateway I run is
country IP block rejecting. If you know that you or your company will
never need to receive email from someone in say Uzbekistan block it.
Again... it just my $0.02.
Eric
Kelly Jones wrote:
> I have about 20 domains, and any email to any of these domains
> (anyaddress at any_of_my_domains.com) forwards to a single mailbox.
>
> I handle email for all these domains myself, but it's becoming a hassle:
>
> % dictionary attacks mean I often get the same spam repeatedly
>
> % I'm too scared to change my SMTP config (to setup graylisting for
> example) for fear of breaking something and losing email [not that
> 99+% of isn't spam anyway...]
>
> % My SMTP server sometimes gets flooded w/ connections (probably not
> denial-of-service-- just excess-of-spammers), delaying legit email.
>
> In short, I want to to give up: running a mail server used to be easy,
> but it's not anymore.
>
> Is there a reliable, fairly inexpensive service that does graylisting,
> razor-checking, sender address verification, RBL-checking, and other
> spam filtering? Specifics:
>
> % I'd like to set the MX records for all 20 domains to their server
> and be done with it.
>
> % I do NOT want to forward email (to a spamarrest.com address for
> example). Forwarding means I still have to run my own mailserver +
> nullifies RBL checks, graylisting, etc.
>
> % I'd like the option of having challenge-response ("you sent me an
> email + I don't know you -- go here and prove you're human"), but
> also the option of turning it off.
>
> % Senders should always be notified (ideally at the SMTP level) if
> their message is rejected (ideally w/ a custom reject message that I
> choose). Messages shouldn't just disappear.
>
> % I'd like the ability to check my email via POP/IMAP. Size limits
> are OK: I plan to download email regularly.
>
> % Most of the email for my domains will come to just me, but I'd like
> the option to forward a copy of emails to certain addresses/domains
> to others. Example: email to *@domain1.com comes to just me, but
> email to foofoo at domain1.com (that makes it through the spam filter)
> comes to me and a copy gets forwarded to bob at gmail.com. This feature
> isn't critical: I can probably setup Pine rules/etc to do what I want
> if I have to.
>
> Any recommendations?
>
>
|
|
