I use Enigmail to sign all my outgoing mail from Thunderbird. If you want to verify that mail is from me, or you want to send me an encrypted email you will need my public key. It should also be available on public keyservers.
My gpg key fingerprint is 4449 9262 CD4F 8DD1 92FC 320B 73F7 C2B3 BA8F 272E