Protocols
Note that all these protocols can be layered atop TLS
POP3 - port 110 ; STARTTLS can be on this port, or on 995 (POP3S)
IMAP - port 143
IMAPS (IMAP over SSL) - port 993
SMTP - port 25; client SW typically use 587 (plaintext) or 465 (TLS)
   ESMTP servers can use TLS; avoid MITM attacks by DANE (part of DNSSEC)
   SMTP-Strict Transport Security (relies on CAs).

OS X 10.4/5 Email Clients
OS X Mail.app - TLS 1.0/1.1
TenFourBird (Thunderbird 38) - email & USENET newsgroups; about:config is in General
    section of Advanced tab ("Config Editor")
Mailsmith - POP3 only
Seamonkey - email & USENET newsgroups

Provider Settings
Comcast
IMAP: imap.comcast.net, port 993 or 143, SSL
SMTP: smtp.comcast.net, port 587 or 465
alpinegmd, bangGash2

CenturyLink/Embarq
username is full email address
    IMAP: mail.centurylink.net, port 993, TLS/SSL
    POP: pop.centurylink.net, port 995, SSL/TLS
    SMTP: smtp.centurylink.net, port 587, STARTTLS
    Crim...: envGash2

Mailfence
   imap.mailfence.com, port 993, TLS/SSL
    smtp.mailfence.com, port 465, TLS/SSL

Newton.org
   Normal IMAP & SMTP ports
   crim...VGX, varFal...

Gmail
   imap.gmail.com, port 993, TLS/SSL
    SMTP: smtp.gmail.com, port 465 or 587, TLS/SSL

Yahoo
   imap.mail.yahoo.com, port 993, TLS
    SMTP: smtp.mail.yahoo.com, port 465 or 587, TLS/SSL yes
    envKan...

Outlook.com/Office 365 mail
   IMAP server = outlook.office365.com, port 993, TLS
    POP3S: outlook.office365.com, port 995, encryption TLS
    SMTP: smtp.office365.com, port 587, STARTTLS , can req. TLS 1.2

Lumos
mail.lumos.net - incoming (110, STARTTLS) & outgoing