Change The Thunderbird Reply Email Layout

Martin Brinkmann
Jun 10, 2009
Updated • Jan 7, 2015
Email, Thunderbird

Whenever a Thunderbird user replies to an email a default layout is being used to add information like the original authors name and email contents to the reply.

Some users may want to change some of the elements that are added automatically. This can be for example useful if the user wants the replies to appear in a specific language that is not the default installation language of the email client. It is also possible to remove or add text or information from replies.

All these parameters are handled in the Thunderbird configuration file. To get there click on [Tools] then [Options] to open the visible settings.If tools is not displayed, tap on the Alt-key to display it.

Now click on the [Advanced] tab and there on the [Config Editor] entry which should open the Thunderbird configuration file which resembles that of the Firefox web browser.

Filter for the term mailnews.reply which should display nine eleven entries that define several options when replying to emails in the Thunderbird email client.

Probably the most interesting parameters in these options are:

  • mailnews.reply_header_authorwrote - Change the default [%s wrote] to something else. The [%s] variable defines the name of the writer of the original email.
  • mailnews.reply_header_ondate - Change the default [On %s] to something else. The [%s] variable defines the date the original email was received.
  • mailnews.reply_header_originalmessage - Change the default [-------- Original Message --------] to something else or remove it completely if you feel it is not needed.

You can change a value by double-clicking on its line in the configuration menu of the Thunderbird email client.

To undo any change, right-click on the name and select the reset option from the context menu to do so.

These preferences allow you to change reply-specific information that are used when you reply to emails in Thunderbird.


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  1. J. Richter said on June 25, 2015 at 4:00 pm

    Any suggestions how to delete the words “RE:”
    from the automatic reply defaults in the subject line?
    The subject is the subject; I don’t need a redundant “Re:” every time a reply goes back and forth.
    Seems another “Re” is attached each reply cycle…. although the message thread remains intact.
    Is it in the config:sys file? Where then?

  2. tasleema petersen said on May 3, 2012 at 10:14 pm

    Good evening

    Hope all is well, I need some advise. I’m totally clueless when it comes to APPLE MAC OS (G3).I’m recently got a MAC by a friend and would like to update the old version to the latest one…can u please help me?

    Kind Regards

  3. Jared said on June 10, 2009 at 11:13 pm

    For anyone who uses Postbox (email client based on Thunderbird), The changes also work with it

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