Real Time Cyrus and Exim Integration (exim,cyrus)

Install

Below please find list of changes required cyrus configuration:

1. Make cyrus wait for unauthenticated lmtp connections over TCP on local interface

   In cyrus.conf add

   SERVICES {
     ...
     lmtp          cmd="lmtpd -a" listen="127.0.0.1:lmtp" prefork=0
   }
   

   Without "-a" lmtp requires authentication for LMTP over TCP.

   If your /etc/services files does not define lmtp service (2003/tcp) then use 'listen="127.0.0.1:2003"'.

Below please find list of changes required in exim's configuration file:

1. Define cyrus_domains domainlist to list all virtual domains handled by your cyrus.

   domainlist cyrus_domains = example.net : example.com : example.org
   

   The best place is just before (or just after) "domainlist local_domains =" line.

2. Define cyrus_ltcp (cyrus local tcp) transport in transports section.

   cyrus_ltcp:
     driver = smtp
     protocol = lmtp
     hosts = localhost
     allow_localhost
   

   It will deliver messages to lmtp port at localhost using lmtp protocol

   If your /etc/services files does not define lmtp service (2003/tcp) then add

   port = 2003
   

3. Insert cyrus_vdom router as first routers section

   cyrus_vdom:
     driver = accept
     domains = +cyrus_domains
     transport = cyrus_ltcp
     no_more
   

   It will select cyrus_lmtp transport for all addresses in cyrus_domains domains.

4. Add checking validity of addresses in cyrus virtual domain in acl_check_rcpt section. I have added the lines just after "accept hosts = :" line [skipping tests for SMTP not over TCP/IP (local)].

     # Reject "faked" sender  addresses in cyrus domains
   
     deny sender_domains = +cyrus_domains
          message        = Sender unknown/invalid
          !verify        = sender/callout=defer_ok,5s
   

   defer_ok makes exim accpet messages when cyrus in unavailable. 5s defines timeout for callout connection attempts.

     # Accept valid (and reject invalid) recipient adresses in cyrus domains
   
     accept domains      = +cyrus_domains
          endpass
          message        = ${if match{$acl_verify_message}\
                           {\N(?m)^\d{3} (\d\.\d\.\d .{0,120})\Z\N} \
                           {IMAP said: $1}{Recipient unknown/invalid}}
          verify         = recipient/callout=random,5s
   

   Whenever Cyrus Imap "reject reply" matches the regular expression, it is passed in "RCPT TO:" by exim. You can customize format of the passed message to fit your tastes.