CB

1. Actually, the 30s timeout is fine, maybe just that the spinning wheel should auto-hide after 8 seconds (medium wait time of a stressed Internet user), rest being non-blocking.
2. Ofc, agree with the new setting "only check if mail does not exist on system" proposal (although it is not a recommended setting for privacy reasons that anyone be able to check if an email is registered on a system or not).
3. The TCP/IP connection refused error message for a SMTP connection on a private user Internet access is indistinguishable from an existing mail server refusing connections from that IP address. In that case, we could just treat the "MX record existing, but connection refused" error case as "neutral" (=uncheckable. No error displayed, but also no "email accepting mail", which is already the case as a greylisting email server (silent timeout). That would solve the "localhost on an ISP blocking SMTP port" (or webserver-only behind a firewall refusing SMTP) case.

Actually, the 30s timeout is fine, maybe just that the spinning wheel should auto-hide after 8 seconds.

That doesn't make any sense from a UX perspective. They won't see it then as they should've moved on from that field. It should probably just give up after 10s.

The TCP/IP connection refused error message for a SMTP connection on a private user Internet access is undistinguishable from an existing mail server refusing connections from that IP address. In that case, you could just treat the "MX record existing, but connection refused" error case as "neutral" (=uncheckable. No error displayed, but also no "email accepting mail", which is already the case as a greylisting email server (silent timeout).

I'm thinking in this case it shows a warning instead of error and yeah the message can be more clear (not say MX record though as most users have no idea what that even is).

Indeed, 30 seconds has become loooong nowadays of faster and faster world. Ok to shorten it to 10 seconds.

I don't recall normal users oriented error messages mentionning "MX". I only have seen in my today's tests in both cases of MX domain not existing and of email address not accepted on server: "This address does not accept email: Needed for confirmation." which seems quite clear and short.

Changing the message from red to orange (as long as contrast makes it readable and accessible) is fine, as it's not a registration-blocking error