from a Mail Transfer Agent (MTA). The request can be made in 2 forms:
- Post Office Protocol (POP3): Messages on the server cannot be flagged (as seen or
forwarded) and messages are removed by default from the server to the MUA.
- Internet Message Access Protocol (IMAP): Messages on the server can be flagged and
directories are used to managed emails on the server.
MUA must meet formating of email header ( To, CC, BCC, Reply-To) and footer as
described in RFC2822.
For firewall settings, MUA access a standard MTA via port 25 (SMTP). Currently
Transport Layer Security (TLS) is being used in many MTA for connection and transfer
security. Other ports of importance (plain/encrypted):
encryption of the Email content is used to protect the sensitive data. This can be in
two forms:S/MIME: requires a trusted body to recognise the userOpenPGP: users can recognise each other (no third party needed)
(E) Support ServersMS Exchange, POP3, IMAP, Lotus
(E) License: LGPL
(T) Calendar: iCalendar, WebDav