Configuring POP and IMAP Servers

SMTP servers tend to attract a lot of attention; after all, Internet mail delivery runs mostly over SMTP. Still, pull mail protocols—POP and IMAP—are just as important in many situations. Typically, users configure their desktop computers’ email clients to contact POP or IMAP servers in order to read their incoming mail. Knowing how to handle these servers’ configurations is therefore quite important. In the simplest cases, this requires launching the servers and setting authentication options. Most sophisticated servers provide additional options, though.

Launching POP and IMAP Servers

POP and IMAP servers vary in how they’re launched. For the popular and simple UW IMAP, the typical method of launching and controlling the server is via a super server. (This method doesn’t scale up very well, though, so for a busy server system, you might want to look into launching the server via a SysV startup script, or even running a server that uses this configuration by default.) On distributions that use xinetd as the super server, the UW IMAP package typically ships with one or more files in /etc/xinetd.d . Typically, each file starts the server to handle a single protocol (POP or IMAP, sometimes with variants for different protocol versions or to add encryption). A typical entry looks like this:

service imap
  socket_type = stream
  protocol    = tcp
  wait        = no
  user        = root
  server      = /usr/sbin/imapd
  disable     = yes

Most distributions disable most or all of the ...

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