FYI, we're finally closing off guest and member accounts entirely. Emails are going to users in batches, so not everybody has received a notification email yet. Everybody will get them, and later we will start adding more obvious warnings on login page and webmail screens.
https://www.fastmail.com/help/account/guest.html
https://www.fastmail.com/help/account/member.html
We have already not allowed new signups at those service levels for quite some time. We are offering very generous discounts for upgrades.
Regards,
Bron.