Then perhaps use the Thunderbird editor to author your HTML as it is described in the user support documentation, then use the addon to do the switching.

https://support.mozilla.org/en-US/kb/signatures#w_html-signatures

Thanks, Matt. I'll try that. Signature Switcher is a great add-on, but not very user friendly.

Matt, I still need a little help. It looks as though Thunderbird only allows one signature per identity. I need multiple signatures per identity. Also, I'm not sure how I get the signature that I created in Thunderbird over to signature switcher. Thanks.

Try this : click on 'Write' / 'New Message'

Remove all content Create the signature from scratch. Save as 'File'

Save in a suitable location eg: In 'Documents' I have a folder called 'Signatures' So I save the file as a html file in 'Signatures' and give it a suitable name like 'Personal' or 'Business'.

In Account Settings for name of account Select the 'Attach the signature from a file instead' Click on 'Choose' Locate that saved signature html file and click on 'Open'

Now clickon 'New Message' It opens showing the 'signature' Save as 'Draft'

Click on 'Drafts' folder select the saved email In the Message Header area - click on 'More' and select 'View Source'

This will show all the html code stuff. look for the line that starts - ok at this it's not helpful that posting code is not working via the usual method.

So I'll post an image - it's below - that shows an example of the bit of code you need to copy

Then open Signature Switch. In 'Signature Switch' Click on 'Add New Signature' Give it a suitable name eg: Formal, Love from Me, etc Paste the copied html stuff into the right side where it says HTML

Where it says 'Auto Switch' you can add specific email address. I have a Personal signature I use when sending emails to my children, so their email addresses are entered in that section and when I select to send to them it gets auto switched in the signature. Click on 'Save'

Now when you click on 'New Message' it may pop up with whatever signature is used in the Account Setting but you click on 'Signature switch' it offers the list of ones you created - select it and it auto swaps to what you want.