I just noticed on a MUUG Round Table e-mail today, the following at the bottom:

Roundtable mailing list -- roundtable@muug.ca
To unsubscribe send an email to roundtable-leave@muug.ca

Regarding the second line (the unsubscribe), I sure hope MUUG at least does SPF/DKIM verification before acting on such an incoming e-mail, because otherwise, a rogue actor out there could unsubscribe any or all of us!

Even so, SPF/DKIM verification would only fully protect those of us (like me) who use our own domain name.

Hartmut