Use mail.(yourdomain).(ext) for all E-mail functions.
Use your full E-mail address as your account name.
Your outbound (SMTP) server requires authentication.
SMTP uses same password as incoming (POP3).
IMAP and Webmail use the same password as incoming, too.
Change outbound (SMTP) port from 25 to 587 (submission).
Always download and save your E-mail.

Use mail.m13.net for all E-mail functions, unless you provided a signed certificate.
Account setup as above. Security is via SSLv3.
Ports: SMTPS = 465, POP3S = 995, IMAPS = 993.
Always download and save your E-mail.
Download and Trust/Install our Root Certificate.
SHA1 = 1F 8D 74 21 82 33 03 3C 6F 26 38 41 07 67 E8 4E 21 E5 49 EE
pkcs7 package also available here.
If you need content security, encrypt via PGP or MIME-S.