14
When an MX lookup fails to reveal that an e-mail address traverses Microsoft servers (lemmy.sdf.org)
submitted 1 year ago by to c/infosec@infosec.pub
17 comments fedilink hide all child comments
 

Before sharing my email address with some person or some org, I do an MX DNS lookup on the domain portion of their email address. It’s usually correct. That is, if the result is not of the form *.mail.protection.outlook.com, then that recipient is not using Microsoft’s mail server.

But sometimes I get stung by an exception. The MX lookup for one recipient yielded barracudanetworks.com, so I trusted them with email. But then they sent me an email and I saw a header like this:

Received: from *.outbound.protection.outlook.com (*.outbound.protection.outlook.com…

Is there any practical way to more thoroughly check whether an email address leads to traffic routing through Microsoft (or Google)?

you are viewing a single comment's thread
view the rest of the comments
[–] [S] 1 point 1 year ago

Well, in that case I guess I should target Barracuda, Proofpoint, and MX Logic in the same way, since 90+% of the world is on MS or Google platforms. That’s probably my practical answer.. to distrust any MX servers that are known to be proxies. So, I need a list of proxies like that.

  • permalink
  • fedilink
  • source
  • parent