[nmglug] Probably a simple answer to spam

Hi all, This is more of a help call and is certainly not specific to GnuLinux but I know many of you are brainiacs and probably have a simple answer. I use Thunderbird, happily. However I've been getting more and more spam emails sent to me from my address. I can block these but I'm concerned there's more to this than meets the eye. Have I been hacked? I hope you all are surviving the fires and other catastrophes that are being visited upon us. Thanks --