@wsmwk I don't believe that's what the OP means. There is not an option to include signatures in the Account Settings menu nor is there an option to include the signature from the Insert menu when you're composing an email.
I think ideally, it should be an option to flag it for all replies AND to include another option in the Insert menu if you decide that a specific email requires the addition of your signature. Right now, I have to go in to the Account Setting menu and copy and paste it into any emails I want to reply to or forward on.
@GCDesign57 That is not what I'm talking about. I'm talking about a feature to add it to an existing email chain. Sometimes I get dropped into a chain at work and I want to make it easy for people to get a hold of me. I have to open that up and copy and paste from that particular menu.
What I want is an easy way, preferably from the Insert menu, to add it to any email I'm writing. Thunderbird lacks that level of control/detail in the settings whereas Outlook has it.