[flomo]

Registration failed for me with a message suggesting such remedies as trying a different email address. Punched in a gmail address and it worked. Perhaps coincidentally.

[johnpowell]

Same with me. It failed with that error when I tried with my fastmail email address. Switched to a gmail one and then it worked.

[WorldWideWayne]

I entered my primary gmail address and got the error. Then I entered my secondary gmail address and it worked.