How to remove the “Received: from” from an e-mails source

emailprivacythunderbird

I'm using:

thunderbird-10.0.3-1.el6_2.x86_64 on Scientific Linux 6.1

and if I send an e-mail (with Gmail) from my Thunderbird then I can see that the e-mail I sent contains a very-very bad thing: 

Received: from [192.168.1.142] (31-149-121-34.pool.myisp.com. [31.149.121.34])

So ALL the e-mail that I'm sending containst my NATed IP address + my public IP address.

Can I delete/remove these lines, so that they will be aren't in ALL the e-mails that I send??

UPDATE:
if I send an e-mail with the gmail web interface, then: 

Received: by 10.112.129.10 with HTTP; Sat, 14 Apr 2012 09:20:13 -0700 (PDT)

Aren't there any Thunderbird Add-ons that modifies my IP Address in the e-mail?

Best Answer

You cannot hide your public IP address (assigned to the WAN interface of your router). You can, however, hide your private IP address (assigned to the NIC of your computer):

  1. Go to Thunderbird's about:config page (in version 3.1 it's Edit > Preferences > Advanced > General > Config Editor).

  2. Find the mail.smtpserver.default.hello_argument preference (if it doesn't exist create it by right-clicking > New > String).

  3. Enter "localhost" (or some other string) as its value.

UPDATE (to answer your update): Mail messages sent via web interfaces (like Gmail's, Hotmail's etc) can have an X-Originating-IP header that shows your public IP. Some services add this header (e.g. Hotmail) and some don't (e.g. Gmail).

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