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 ----------------- Gmail : imap.gmail.com, port 993, TLS/SSL SMTP: smtp.gmail.com, port 465 or 587, TLS/SSL crim...,envKan ; bergs..., Yahoo: imap.mail.yahoo.com, port 993, TLS SMTP: smtp.mail.yahoo.com, port 465 or 587, TLS/SSL yes envKan... 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... 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