[Dovecot] BlackBerry will not setup my POP3 email, all other mail clients fine

[Ian Solecki]

Hello, hoping someone here might be able to help me or at least point me in
the right direction.

My company recently (last week) moved to a new dedicated server for website
and email hosting. It is a fairly run-of-the-mill Linux machine running
cPanel and Dovecot (with the BlackBerry Fastmail service enabled) as a mail
server.

When we first set up the server, I was able to create a mailbox, access it
via any desktop mail client, webmail, AND by setting it up as a basic POP3
account on my BlackBerry. Mail was running fine to and from the BlackBerry,
no problems.

I deleted that account from my BlackBerry as it was a test account, and
went to add my actual account but was unable to do so. Received the "Cannot
log in. Verify your email address, user name and password. If the error
persists, contact (my domain name)" message. I tried the test account that
had been running successfully and sending/receiving emails not minutes
earlier, and it would not set up either.

I have since tried multiple accounts on multiple BlackBerry devices
(different models) on multiple carriers on several of my different domains
(all of which point to the same server, of course), to no avail.

Yet, any of these accounts still work flawlessly in any desktop mail client
(Outlook, OE, Thunderbird, iPad, iPhone, etc). Also, any of these
BlackBerrys work flawlessly with any other mail server.

The username to log in to these mailboxes is not standard, it's mailboxname+
example.com if the email address is mailboxname at example.com and the mail
server is mail.example.com. So, I know I have to access the "Advanced
Settings" in BlackBerry email setup in order to put this username in.
Still, no effect.

So, there is something wrong with how mail SETUP works (not
sending/receiving, though that may also not work, I have no way of knowing
now) between RIM and my server, and it's something that has changed since
the server was set up a week ago.

My carrier(s) are clueless, my dedicated server provider (Lunarpages) is
clueless. Can anyone help?