Internal server address visible on header.

[Splat]

I was having some issues sending/recieving email to outside mail address's (gmail, hotmail) when I started poking around and looking at the headers coming from our server I noticed that our internal mail server nat address was in the header when I looked at the mail on my hotmail account. Thinking that this was incorrect I opened a case with support and the response I got was that this was completely normal. After looking at mail from 10 other mail servers I found none of them had the internal nat address in the header. My question is how many other zimbra customers/users are seeing their servers sending out internal nat address's? And if so what needs to be changed on my config to resolve the problem. Any feedback would be helpfull.

[phoenix]

If you mean the headers in this post they are perfectly normal. That 127.0.0.1 address is the loopback address and isn't an internal NAT address, mail from my server looks exactly the same as that and I'm not having problems. The reason you'll find 127.0.0.1 in the ehaders is that's the ip address zimbra uses to pass stuff between the components such as amavisd-new in the case of your other post.

[dijichi2]

I think possibly he's referring to his server's internal IP address as opposed to the external IP mapped through NAT. In this case, it's perfectly normal for the headers to show the internal IP - there's no way of the server inserting NAT ip's without some seriously questionable resolver setup. It won't hurt sending emails to the outside. have a look in the logs for the real reason.

[Splat]

It shows my 10.10.x.x address in the header on the mail sent from my zimbra server to the outside mail server when I look at the mail from the outside server.

By this thinking anyone that recieves mail from our server could get the internal address without a problem. Wouldnt that be a security issue?

[phoenix]

I'm surprised it shows that address but, no, it's not a security issue. Internal addresses are non-routable and you're behind NAT anyway. Besides, if you have port 25 open to your mail server isn't that a security issue?

[dijichi2]

the only security issue is that it exposes a tiny amount of your internal logical network infrastructure - it's for this reason for instance you should always disable public zone dumping on your dns server. but in this case it's unavoidable (well, it's possible but difficult) and a very small risk.