Lukas Beeler’s IT Blog

Hostpoint is having problems with their IMAP servers again.

The problem is not obvious to find. They use DNS round robin to distribute their load, and they currently have 4 IMAP servers:

;; ANSWER SECTION:
imap.example.com.      300     IN      CNAME   imap.mail.hostpoint.ch.
imap.mail.hostpoint.ch. 300     IN      A       217.26.49.203
imap.mail.hostpoint.ch. 300     IN      A       217.26.49.202
imap.mail.hostpoint.ch. 300     IN      A       217.26.49.200
imap.mail.hostpoint.ch. 300     IN      A       217.26.49.201

Now the problem is that three of these four mailservers work correctly, and the fourth just refuses all authentication attempts:

% telnet 217.26.49.200 143
Trying 217.26.49.200...
Connected to 217.26.49.200.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 UIDPLUS *snip*
2 login "info@example.com" "mypw"
2 NO Login failed.

% telnet 217.26.49.201 143
Trying 217.26.49.201...
Connected to 217.26.49.201.
Escape character is '^]'.
* OK [CAPABILITY IMAP4rev1 UIDPLUS *snip
2 login "info@example.com" "mypw"
2 OK LOGIN Ok.

The fix right now is to just configure the client to use one of the working IP addresses - but be aware that this might lead to problems further down the road when the machine is down for maintenance etc.