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Catching emails with fake return addresses

post #1 of 6
Thread Starter 
I was wondering if anyone knew about a Thunderbird add-on that would catch these fake emails. I recently had a business competitor send an email through http://emkei.cz/ with the return/sender address set to look like one of my own partners in an attempt to have me contact him through another method, so he could continue posing as my partner in order to obtain confidential information. Luckily I realized that the wording was off, as I've been friends with this particular business partner since we were kids and I knew he was phrasing things in a way that he doesn't usually speak; I checked the headers, saw emkei.cz in it and knew it was fake.

However I would like to set up an automatic block or flag for things like this, just to ensure I nor any of my friends/family/staff are caught off-guard in the future. Would this be possible in Thunderbird?
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post #2 of 6
What you're looking for is SPF filtering. SPF stands for Sender Policy Framework and is a set of DNS records (TXT records) that specify from which servers are allowed to send mail for a particular domain. Receiving mail servers participating in SPF will look at the sending IP for the e-mail, and then check the SPF record for the domain - if the IP address is not in the allow list, the e-mail will either be quarantined or tagged as spam.

Now, I notice you mentioned about Thunderbird - technically SPF could be implemented on the client side - so see if an add-on for SPF exists for Thunderbird. Otherwise, I assume you are using POP/IMAP, in which case you can use Xeams - the eXtended Email And Mesasing server which can sit between your POP or IMAP server and your mail client.
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post #3 of 6
Thread Starter 
So would I need to add the domains to the allow list manually? That's the part I didn't really understand, as I'm not receiving mails from gmail/yahoo accounts but rather private domains. Adding them manually for my own domain would be fine to catch fake mails from my own business partners, but I would preferably want a system of catching these universally so if someone tried to pose as a contact from another company and I hadn't added them to my list, it would still catch that.
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post #4 of 6
You should be able to turn on reverse lookups on your mail server, depending on what you're using.
This would query the origination server in question's IP back to the appropriate public MX record. If it's a mismatch, it will mark the message as spam.
post #5 of 6
Quote:
Originally Posted by a!!!!1 View Post

So would I need to add the domains to the allow list manually? That's the part I didn't really understand, as I'm not receiving mails from gmail/yahoo accounts but rather private domains. Adding them manually for my own domain would be fine to catch fake mails from my own business partners, but I would preferably want a system of catching these universally so if someone tried to pose as a contact from another company and I hadn't added them to my list, it would still catch that.

No SPF is managed by the administrators of the sending domain - you don't have to add anything to an allow list. It only works if the domain administrator is participating in SPF.
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post #6 of 6
Quote:
Originally Posted by beers View Post

You should be able to turn on reverse lookups on your mail server, depending on what you're using.
This would query the origination server in question's IP back to the appropriate public MX record. If it's a mismatch, it will mark the message as spam.

Unfortunately not everyone plays by this rule frown.gif
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Ol' Sandy
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"Zeus"
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