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SMTP, spam and autoturn, any insight?

Patch
Grafter
Posts: 122
Registered: 30-07-2007

SMTP, spam and autoturn, any insight?

We are looking at ways of reducing the amount of spam we recieve, especially the large volume of spam that is sent to no existent users on our domains.

At the moment all email to our domain is collected via pop by our mailserver (windows 2000 running mDaemon). As a result any mail addressed to anything@ourdomain.co.uk, even if it is not a valid email account, ends up here.

I was thinking that if we set up our mail to be received via smtp we would then be able to refuse to accept mail that is not for one of our accounts.

Is this correct? or will it simply mean the mail is then passed on to autoturn, and we then have to collect it from there?

Does anyone have experience of this and any advice to offer?

Patch
9 REPLIES
N/A

SMTP, spam and autoturn, any insight?

It depends on what software you use for processing your mail. (What SMTP software you use, rather than what mail client)

I use Exchange 2000 Enterprise which returns all incorrectly addressed mail to the sender. (Which is often spoofed, so it goes either a) nowhere, or b) to some other poor chappie who has had their domain spoofed.)

Not sure on cheaper (or free) alternatives, but I presume they work in the same manner.

The same thing could be achieved by setting up mailboxes via the portal for the named addresses you wish to use, and then you can get PN to blackhole everything else.
lingbob
Grafter
Posts: 734
Registered: 05-04-2007

SMTP, spam and autoturn, any insight?

I ran the Mercury mail server for a while which can be configured to reject all unknown RCPT's. That one tweak alone cut down the amount of spam enormously Cool
Patch
Grafter
Posts: 122
Registered: 30-07-2007

SMTP, spam and autoturn, any insight?

The mailserver software we are running is mDaemon which is a full mailserver product. So it has all these features to reject mail, but I was not sure if simply rejecting mail would result in it being passed onto the next mx which i guess would be autoturn.

Then if mail is sent through autoturn, can our server still refuse to accept it?... Or am I imagining a problem that simply will not be there.

Thanks for any help or advice that may enlighten me!

Patch
N/A

SMTP, spam and autoturn, any insight?

Mine is set up to receive all mail for a number of domains.

It then tries to deliver the messages into internal mailboxes - any incorrectly addressed are deleted, and an NDR is sent to the sender.
Patch
Grafter
Posts: 122
Registered: 30-07-2007

SMTP, spam and autoturn, any insight?

So sallyandjames, you actually accept all the email first and then return anything you don't want?

Is this the normal way?

I know that the mailserver software we have has various settings where mail can be "refused". In which case I understood that the whole mail would never actually be recieved at our end, and turned away during the initial smtp communication.

The reason I thought this was better than recieveing then returning is that to return a spoofed mail causes headaches for some other individual (I know, it has happened to us!).

Where as, as I underestand it, refusing to accept the mail in the first place, would be something that the sending computer (i.e. spammer) would have to deal with.

Or have I misunderstood this.

It may be that the pop black hole solution is the one we go for, it just concerns me that if someone legitimately sends an email to our company, but mistypes the address, the mail will simply disappear, with neither us, nor the sender realising.

Any thoughts?

Patch
lingbob
Grafter
Posts: 734
Registered: 05-04-2007

SMTP, spam and autoturn, any insight?

Quote
The mailserver software we are running is mDaemon which is a full mailserver product. So it has all these features to reject mail, but I was not sure if simply rejecting mail would result in it being passed onto the next mx which i guess would be autoturn.

No, it wouldn't be passed on to the next MX, the mail session would be terminated. BUT ... there's nothing to stop the spammers from by-passing your own mail server and mailing direct-to-mx. This is exactly what a lot of them do and the only defence against that is to block the PlusNet MX servers. Snag with that is, that mail will be then stored on autoturn and as soon as you finger autoturn, it all comes flooding in - can't win!
Patch
Grafter
Posts: 122
Registered: 30-07-2007

SMTP, spam and autoturn, any insight?

Thanks Martin and James,

That certainly explains things. So neither option of using a blackhole for all pop email, or using the smtp server sound like they will solve the problem, but both sound better than our current situation.

Thanks for your help

Patch
N/A

Spam

Set the Mdeamon as the smtp and update the mx with PN, everthing then will go into a spamfolder or bounce depending on your options.
I personaly want PN to setup SPF (sender policy framework) to stop these lowlifes spoofing domains and sysadmins bouncing everthing, which only adds to the bottleneck
Patch
Grafter
Posts: 122
Registered: 30-07-2007

SMTP, spam and autoturn, any insight?

Ok, we have decided to try the smtp route, but I just wanted to check the best setting for the reverse dns. I understand that I need to raise a ticket and ask support to update this for us... but what to?

We currently have two domains that we recieve emails from. however we only ever send mail from users on one of these domains. So should the rdns be set to mail.ourdomain.co.uk, or to ourdomain.co.uk, or to username.plus.net

Thanks

Patch