Question:
How to get rid of those annoying double dashes before the message signature?

 

Answer:
1. Open the Config Editor (Tools -> Options or Edit -> Preferences and then Advanced -> Config Editor)
2. Search for: mail.identity.default.suppress_signature_separator
3. Set it to TRUE by double-clicking it.

Now all new emails are created without the -- before the signature.


Update: In recent times when creating or replying to email messages, I have noticed that my signature appears faded or greyed out.
The signature started to appear this way after upgrading to version 17.08. After a bit of research, it turns out that Thunderbird uses a
<div class="moz-signature"> tag.

To suppress this tag from effecting the appearance of your signature add a </div> tag in your signature file one line below the <body> tag.
Your signature will now appear as normal.

Here is an example from my signature file:

<body text="#000000" bgcolor="#FFFFFF">
</div> <!-- This suppresses Thunderbird's <div class="moz-signature"> tag -->
<a href="http://www.sauveconsulting.com.au"><img src=