[by sven @ Mon Jul 14 12:18 CEST 2003]
Since the old days e-mail is send over the internet by SMTP (Simple Mail Transfer Protocol), but the starting point from SMTP is that the receiver is online permanently. With the coming of computers (with telephone modems) that aren't always online, alternatives for SMTP are thought of. POP3 (Post Office Protocol) is the most used protocol. Hereby all incoming e-mail is stored on the server from the ISP (Internet Service Provider). People can then connect to the internet and get their e-mail from this server.
Another possibility is bSMTP (batched SMTP). Hereby e-mail is send by SMTP as soon as the computer gets online. If the computer is offline, the mail is saved on the server from the ISP and is send as soon as the computer is connected to the internet.
For setting up freegw to use bSMTP I used the bsmtp en sendmail mini-howto (in Dutch) from Erik Hensema. Sendmail is a MTA (Mail Transport Agent) that receives and sends mail between other hosts. I copied /etc/mail/freebsd.mc to /etc/mail/bsmtp.mc and added the sendmail configuration directives SMART_HOST, MASQUERADE_AS and LUSER_RELAY to /etc/mail/bsmtp.mc. Then I converted the bsmtp.mc file is to a sendmail configuration file with the extension .cf with the macro processor m4. In the firewall I opened port 25 for incoming packets from the mailservers from my ISP. Also I upgraded to FreeBSD 4.8-STABLE and with this sendmail 8.12.9, because sendmail < 8.12.9 has a critical security problem.
One of the advantages of bSMTP is that I can now use an infinite number of e-mail addresses. Another advantage is that my mailbox on the server from my ISP (which has a maximum size of 15MB) never gets full, because all mail is send directly to freegw. Also I like the e-mail address <firstname.lastname@example.org> much more then just <email@example.com>.
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