Thunderbird includes NAT ip in mail headers

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Sniffle Dog!!!
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Thunderbird includes NAT ip in mail headers

Post by Sniffle Dog!!! »

hi,

does anyone know how to keep thunderbird from including your PC's NAT ip address (ex. 192.168.1.1) in the headers? other email programs (Outlook) don't include the NAT address in the headers so i'm hoping there is a way to keep Thunderbird from including it, maybe in the config editor? i don't know, either way any help is appreciated.

~ Sniffle Dog!!!
rsx11m
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Post by rsx11m »

If your IP address is not a "fully qualified domain name" (FQDN), the IP address itself will be used for outgoing e-mail when greeting the SMTP server. If you have NAT inbetween, the local address is not an FQDN and will therefore be used as the argument. However, you can override this in the configuration editor Tools > Options > Advanced > General > Config Editor. Type "smtp" into your search bar, then find out which SMTP server you would like to specify the outgoing name for (it will have a number 1, 2, 3, etc.). Then right-click into the window and select New > String, and enter the following:
  • Name of the preference is: mail.smtpserver.smtp*.hello_argument
  • Value: whatever.you.want.com
where you have to replace * with the SMTP server number. You can set this separately for all SMTP servers. (I've tried this for SeaMonkey, but the same should work for Thunderbird.)
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DanRaisch
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Post by DanRaisch »

rsx11m, that works well in TB also. Thanks for the tip!
Sniffle Dog!!!
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Post by Sniffle Dog!!! »

rsx11m,

that worked perfectly, thanks a million billion.

~ Sniffle Dog!!!
rsx11m
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Post by rsx11m »

You are welcome! Actually, I think it's even taking the IP address for the "Hello" argument if you are connected directly to the internet and thus have an officially registered DNS entry, but that preference is a way how to enforce a specific greeting for sure.
alanrf
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Post by alanrf »

The IP address range starting 192.168.1 is reserved for the type of LAN that almost all of us run in our homes.

It might as well say "My home system". It is nothing private to you, it discloses nothing about you and, in fact gives the same anonymity as millions of us.
rsx11m
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Post by rsx11m »

Alan, this is certainly correct. Those local network numbers (192.168.x.x, 172.{16-31}.x.x, and 10.x.x.x) don't have any meaning outside of the local network and won't be routed into any other network beyond whatever is specified in the NAT setup. They could only be exploited if somebody manages to break into your router, DSL or cable modem. Nevertheless, some people may prefer to hide the internal structure of what they have at home from others. Thus, while I don't see a compelling reason to hide that number, I also don't see any reason why not to hide it.
alanrf
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Post by alanrf »

Completely agree.

Some folks though still believe this range is personal to them and discloses something private about them. I was just clarifying (as you did more completely - thanks) the use of local network numbers.
rsx11m
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Post by rsx11m »

Ok, it was a bit ambiguous whether or not you were arguing against hiding the number as such. What I've noticed though is that the name you choose to replace the number with has some impact on the spam score of your message. Following the (rather extensive) discussion around Bug 279525, comment #19, I've tested the score for the numerical IP address, with an arbitrary value, and the correct base domain as arguments. Only the arbitrary value received a "forged hello" penalty by SpamAssassin, not the other ones. Thus, whatever you choose, make sure it is sufficiently related to the domain you are sending the e-mail from to avoid getting hit by spam filters!
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