Folks, I understand your concern. I get plenty of spam too, but listen to Alan. This is real. You don't hear from Matt Alberti very often but he is on the AMSAT IT team. I have done the transition for some of the internal mailing lists, so I can tell you that the bb mail will likely continue to flow if you do nothing. You will need to sign up for any of the following:
1) You have email aliases (that is you send from more than the same email address that you get your bb mail on)
2) You ever want to turn on "vacation mode", that is temporarily turn off your bb mail.
3) If you get digests, I'm not sure if you will continue to. You will have to sign up to change this setting.
4) If you ever want to look at the bb archives you may have to sign up.
I hope this helps, and good for you for being careful and suspicious. Of course you don't need to believe me either :-)
73,
Burns, WB1FJ