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Editing: LMTP.Exim.txt
Contents 1. Using LMTP over UNIX Socket 2. Using LMTP over TCP Socket 3. Striping domain to avoid user unknown / doesn't exist error 4. Verifying recipients using LMTP 5. Delivering mails case insensitively Exim provides support for LMTP over UNIX sockets using the LMTP transport [http://www.exim.org/exim-html-current/doc/html/spec_html/ch-the_lmtp_transport.html], your distribution may/not provide this, run exim -bV and check for 'lmtp' in 'Transports:'. Support for LMTP over TCP sockets is provided by the SMTP transport [http://www.exim.org/exim-html-current/doc/html/spec_html/ch-the_smtp_transport.html]. Using LMTP over UNIX Socket --------------------------- Use this configuration if dovecot runs on the same host as exim. Example router: ---%<------------------------------------------------------------------------- local_user: debug_print = "R: local_user for $local_part@$domain" driver = accept domains = +local_domains check_local_user transport = dovecot_lmtp cannot_route_message = Unknown user ---%<------------------------------------------------------------------------- Example transport: ---%<------------------------------------------------------------------------- dovecot_lmtp: driver = lmtp socket = /var/run/dovecot/lmtp #maximum number of deliveries per batch, default 1 batch_max = 200 #allow suffixes/prefixes (default unset) rcpt_include_affixes ---%<------------------------------------------------------------------------- Using LMTP over TCP Socket -------------------------- Example router: ---%<------------------------------------------------------------------------- local_user: transport = dovecot_lmtp domains = +local_domains driver = manualroute route_list = "* 192.168.1.0 byname" #if destination server is the local host enable this #self = send ---%<------------------------------------------------------------------------- Set IP and port as appropriate to your setup. Example transport: ---%<------------------------------------------------------------------------- dovecot_lmtp: driver = smtp #allow suffixes/prefixes (default unset) rcpt_include_affixes protocol = lmtp port = 2525 ---%<------------------------------------------------------------------------- Striping domain to avoid user unknown / doesn't exist error ----------------------------------------------------------- If you are using a userdb which does not have domain names, you may need to add a setting to 20-lmtp.conf ---%<------------------------------------------------------------------------- protocol lmtp { ... # use %n to strip away the domain part auth_username_format = %n } ---%<------------------------------------------------------------------------- Symptoms: * Exim says something like "LMTP error after RCPT ... 550 ... User doesn't exist someuser@somedomain" * Dovecot verbose log says something like "auth-worker(9048): passwd(someuser@somedomain): unknown user" Verifying recipients using LMTP ------------------------------- You can use callout verification to avoid accepting mail for addresses which do not exist in Dovecot. Below is a config snippet which could be used in acl_smtp_rcpt to achieve this: ---%<------------------------------------------------------------------------- deny message = invalid recipient domains = +local_domains !verify = recipient/callout=no_cache ---%<------------------------------------------------------------------------- For more information on address verification see the related section of the Exim specification [http://www.exim.org/exim-html-current/doc/html/spec_html/ch-access_control_lists.html#SECTaddressverification]. Delivering mails case insensitively ----------------------------------- *Warning: *Just use this setup if all your login names contain only lower case characters! (On Linux see /etc/adduser.conf under NAME_REGEX variable). Exim retains the case of the local part. Dovecot's LMTP /may/ fail looking up an incorrect cased local part in your userdb. You can solve this problem by extending the /protocol lmtp/ section: ---%<------------------------------------------------------------------------- protocol lmtp { ... # use %Ln to strip away the domain part auth_username_format = %Lu } ---%<------------------------------------------------------------------------- (If you don't mind allowing case insensitive logins for dovecoth authentication, you may set /auth_username_format/ in the global configuration accordingly and renounce the above change). In case you prefer to configure exim to lower case the local part instead, add a router just before your local delivery router: ---%<------------------------------------------------------------------------- lowercase_local: debug_print = "R: lower case local_part for local delivery" driver = redirect redirect_router = local_user data = ${lc:${local_part}} ---%<------------------------------------------------------------------------- Make sure to reference the name you have chosen for your local delivery router within /redirect_router/. (This file was created from the wiki on 2019-06-19 12:42)
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