pop3proxyd - Cyrus IMAP documentation

       The Cyrus Team

       1993–2025, The Cyrus Team

3.10.2                                            Jun 27, 2025                                     POP3PROXYD(8)

pop3d is an POP3 server.  It accepts commands on its standard input and responds on its standard  output.
       It MUST be invoked by master(8) with those descriptors attached to a remote client connection.

       pop3d reads its configuration options out of the imapd.conf(5) file unless specified otherwise by -C.

       If  the  directory  log/user  exists  under  the directory specified in the configdirectory configuration
       option, then pop3d will create protocol telemetry logs for sessions authenticating as user.

       The telemetry logs will be stored in the log/user directory with a filename of the pop3d process-id.

pop3d is commonly included in the SERVICES section of cyrus.conf(5) like so:

          SERVICES {
              imap        cmd="imapd -U 30" listen="imap" prefork=0
              imaps       cmd="imapd -s -U 30" listen="imaps" prefork=0 maxchild=100
              pop3cmd="pop3d-U30"listen="pop3"prefork=0pop3scmd="pop3d-s-U30"listen="pop3s"prefork=0maxchild=100
              lmtpunix    cmd="lmtpd" listen="/var/run/cyrus/socket/lmtp" prefork=0 maxchild=20
              sieve       cmd="timsieved" listen="sieve" prefork=0
              notify      cmd="notifyd" listen="/var/run/cyrus/socket/notify" proto="udp" prefork=1
              httpd       cmd="httpd" listen=8080 prefork=1 maxchild=20
          }

       /etc/imapd.conf

       pop3proxyd - Cyrus IMAP documentation

       This  is a hard linked copy of pop3d(8), retained for backwards compatibility from when a murder frontend
       used its own pop3d binaries.

-Cconfig-file
              Use the specified configuration file config-file rather than the default imapd.conf(5).

       -Uuses
              The maximum number of times that the process should be used for new  connections  before  shutting
              down.  The default is 250.

       -Ttimeout
              The  number of seconds that the process will wait for a new connection before shutting down.  Note
              that a value of 0 (zero) will disable the timeout.  The default is 60.

       -D     Run external debugger specified in debug_command.

       -s     Serve POP3 over SSL (pop3s).  All data to and from pop3d is encrypted  using  the  Secure  Sockets
              Layer.

       -k     Serve MIT's KPOP (Kerberized POP) protocol instead.

       -pssf Tell  pop3d  that  an  external  layer  exists.   An  SSF (security strength factor) of 1 means an
              integrity protection layer exists.  Any higher SSF implies some form of privacy protection.

imapd.conf(5), master(8)

pop3d [ -Cconfig-file ] [ -Uuses ] [ -Ttimeout ] [ -D ]
              [ -s ] [ -k ] [ -pssf ]