Ability to quickly switch signatures.

[Wojtek_Sz]

I send messages from one email address using multiple signatures (e.g. private, work, and club or association). It would be a great convenience if you could choose a signature when creating a message.

[Jon]

Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.

[MattAuSupport]

Perhaps use the addon that offers that functionality.

https://addons.thunderbird.net/en-US/thunderbird/addon/signature-switch/?src=search

[PSz]

Postbox has this functionality well designed.

Signature list is edited/managed separately.

And can be choose for each identity as preferred signature.

In compose window you can easily override signature from list.