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Recently I have been receiving emails that apparently originate from my account about Russian hackers, I've set up an SPF record to try and stop this but it has made no difference and I have updated my password to rule out the idea of it being a compromised account.

Is there anything else I can do to prevent this?

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Are you able to check to see if they actually hacked your password and are sending through your SMTP server? –  steve Apr 2 '13 at 13:01
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2 Answers

0, there are no controls in SMTP for verifying the sender (if you want to get technical, 0 outside the server that is responsible for the domain your email address belongs to). Anyone can send a mail with your email address on it.

I'd have a look at some of the other methods for intercepting spam, spamassassin, RBLs, and other things you can implement on the mailserver level to reduce the amounts of email like this you see.

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I have Spam Assassin and I've set it to be quite ruthless too, is there anything else I can do? I'm not a server wizz but I can get by. –  Dave Mackintosh Apr 2 '13 at 9:10
    
Well, I'd imagine what you're seeing is called backscatter, basically, someone send s a bunch of email ostensibly from your address to many other addresses, some which don't work, just so they get sent back to your server as "undelivered". Have a look at some of the spamassassin plugins, the blacklists may help.. also see how close the emails arrive to your spam threshold, you may want to adjust some points in the rules. –  NickW Apr 2 '13 at 9:15
    
Perhaps if I put my SPF record here you could help me with it? –  Dave Mackintosh Apr 3 '13 at 15:31
    
I'm sure we can help you with it, but I'm not sure it will help you much, you'd need the people backscattering you to actually respect SPF records. –  NickW Apr 3 '13 at 16:19
    
:/ that really blows, getting between 30 and 50 of them a day now. Most frustrating. I will do some research into what I can and can't do and report back as soon as I can for your advice. –  Dave Mackintosh Apr 4 '13 at 10:49
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As NickW said, anybody can send an email using any sender email address at all, just like I could send a piece of paper mail and put your name and address on the back - and if the letter can't be delivered, it will be returned to your address instead of mine.

The only thing you can do to protect against this is what you've already done, i.e. using SPF. But it's up to the recipients to check for SPF records, and not all of them do, or they don't do it before rejecting the mails.

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DKIM would help, too, but servers which don't even respect SPF are not very likely to respect DKIM too. –  GDR Apr 2 '13 at 12:09
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