Yes, that was it. I had a non-common TLD in the email domain. com/net/org are no problem but it seems that many country TLDs and generic TLDs are not working. Thanks for pointing me in the right direction but can I suggest that you tweak the email validation algo, so that it allows basically anything as TLD. Otherwise you'll always end up missing some new or more exotic TLDs.

While you're at it, please also make sure you support "plus addressing", and let people change their email in the profile settings without having to email you...

Email address validation is not easy, you'd be surprised what weird things can be in valid email addresses ;-)

I'm now going to check it out in more detail.

Thanks for sharing this - and happy birthday from me as well.