Send a message via SMTP and read it via IMAP using localhost domain

[soywod]

As I mentioned in #281, I try to use your server as a lib, for testing purpose. I set up local principals alice@localhost and bob@localhost. Bob tries to send a message to Alice, but I get the following logs:

2024-03-06T14:32:07.407597Z  INFO utils: Starting Stalwart Mail Server v0.1.0...
2024-03-06T14:32:07.408840Z DEBUG store::backend::sqlite::pool: SQLITE_BUSY, retrying after 200ms (attempt 0)
2024-03-06T14:32:07.409063Z DEBUG store::backend::sqlite::pool: SQLITE_BUSY, retrying after 200ms (attempt 0)
2024-03-06T14:32:07.409067Z DEBUG store::backend::sqlite::pool: SQLITE_BUSY, retrying after 200ms (attempt 0)
2024-03-06T14:32:07.609337Z DEBUG store::backend::sqlite::pool: SQLITE_BUSY, retrying after 200ms (attempt 1)
2024-03-06T14:32:07.609337Z DEBUG store::backend::sqlite::pool: SQLITE_BUSY, retrying after 200ms (attempt 1)
2024-03-06T14:32:07.836346Z  WARN smtp::config::resolver: No public suffixes list was specified.
2024-03-06T14:32:07.841709Z DEBUG jmap::services::housekeeper: Housekeeper task started.
2024-03-06T14:32:07.841943Z  INFO utils::listener::listen: Starting listener id="imap" protocol=Imap bind.ip="::" bind.port=50750 tls=false
2024-03-06T14:32:07.842173Z  INFO utils::listener::listen: Starting listener id="smtp" protocol=Smtp bind.ip="::" bind.port=53112 tls=false
2024-03-06T14:32:07.856812Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::ehlo: context="spf" event="lookup" identity="ehlo" domain="soywod" result=None
2024-03-06T14:32:07.856914Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::ehlo: context="ehlo" event="ehlo" domain="soywod"
2024-03-06T14:32:07.857203Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::auth: context="auth" event="authenticate" result="success"
2024-03-06T14:32:07.857977Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::mail: context="iprev" event="lookup" result=pass ptr="localhost."
2024-03-06T14:32:07.858041Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::mail: context="spf" event="lookup" identity="mail-from" domain="soywod" sender="alice@localhost" result=None
2024-03-06T14:32:07.858073Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::mail: context="mail-from" event="success" address="alice@localhost"
2024-03-06T14:32:07.858306Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::rcpt: context="rcpt" event="success" address="bob@localhost"
2024-03-06T14:32:07.899338Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::data: context="dkim" event="verify" return_path="alice@localhost" from="alice@localhost" result=[]
2024-03-06T14:32:07.899489Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::data: context="arc" event="verify" return_path="alice@localhost" from="alice@localhost" result=none
2024-03-06T14:32:07.899617Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::data: context="dmarc" event="verify" return_path="alice@localhost" from="alice@localhost" dkim_result=none spf_result=none
2024-03-06T14:32:07.900850Z  INFO session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::queue::spool: Message queued for delivery. context="queue" event="scheduled" id=162436015245357056 from="alice@localhost" nrcpts=1 size=901
2024-03-06T14:32:07.902896Z DEBUG delivery{id=162436015245357056 return_path="alice@localhost" nrcpt=1 size=901}:attempt{domain="localhost" attempt_number=0}: smtp::outbound::delivery: Failed to retrieve MTA-STS policy: Record not found: NoError context="sts" event="policy-fetch-failure"
2024-03-06T14:32:07.903034Z  INFO delivery{id=162436015245357056 return_path="alice@localhost" nrcpt=1 size=901}:attempt{domain="localhost" attempt_number=0}: smtp::outbound::delivery: context="dns" event="mx-lookup-failed" reason=DNS record not found: No Error
2024-03-06T14:32:07.904504Z  INFO delivery{id=162436015245357056 return_path="alice@localhost" nrcpt=1 size=901}: smtp::queue::spool: Message queued for delivery. context="queue" event="scheduled" id=162436015253745665 from="<>" nrcpts=1 size=2054
2024-03-06T14:32:07.905373Z  INFO delivery{id=162436015245357056 return_path="alice@localhost" nrcpt=1 size=901}: smtp::outbound::delivery: Delivery completed. context="queue" event="completed"
2024-03-06T14:32:07.907706Z DEBUG delivery{id=162436015253745665 return_path="<>" nrcpt=1 size=2054}:attempt{domain="localhost" attempt_number=0}: smtp::outbound::delivery: Failed to retrieve MTA-STS policy: Record not found: NoError context="sts" event="policy-fetch-failure"
2024-03-06T14:32:07.907853Z  INFO delivery{id=162436015253745665 return_path="<>" nrcpt=1 size=2054}:attempt{domain="localhost" attempt_number=0}: smtp::outbound::delivery: context="dns" event="mx-lookup-failed" reason=DNS record not found: No Error
2024-03-06T14:32:07.907990Z  INFO delivery{id=162436015253745665 return_path="<>" nrcpt=1 size=2054}: smtp::queue::dsn: Failed delivery of message with null return path. context="queue" event="double-bounce" id=162436015253745665 failures=["<alice@localhost> (failed to lookup 'localhost': Domain not found: NoError)\r\n"]
2024-03-06T14:32:07.908413Z DEBUG smtp::queue::spool: Failed to lock event: Event already locked. context="queue" event="locked" id=162436015253745665 due=1709735527
2024-03-06T14:32:07.909645Z  INFO delivery{id=162436015253745665 return_path="<>" nrcpt=1 size=2054}: smtp::outbound::delivery: Delivery completed. context="queue" event="completed"
2024-03-06T14:32:08.912622Z DEBUG session{instance="smtp" protocol=Smtp remote.ip="::1" remote.port=52964}: smtp::inbound::spawn: Connection closed by peer. event="disconnect" reason="peer"
2024-03-06T14:32:08.914455Z DEBUG session{instance="imap" protocol=Imap remote.ip="::1" remote.port=57510}: imap::core::session: Disconnecting client. event="disconnect"
2024-03-06T14:32:08.914839Z DEBUG utils::listener::listen: Listener shutting down. event="shutdown" instance="imap" protocol=Imap
2024-03-06T14:32:08.914900Z DEBUG utils::listener::listen: Listener shutting down. event="shutdown" instance="smtp" protocol=Smtp

Looks like localhost is not resolved:

2024-03-06T14:32:07.907990Z INFO delivery{id=162436015253745665 return_path="<>" nrcpt=1 size=2054}: smtp::queue::dsn: Failed delivery of message with null return path. context="queue" event="double-bounce" id=162436015253745665 failures=["<alice@localhost> (failed to lookup 'localhost': Domain not found: NoError)\r\n"]

My test fails because it does not find the message in its inbox, so the message is not delivered.

How can I make it work?

EDIT: I precise that I have enabled the local_delivery cargo feature: smtp = { git = "https://github.com/stalwartlabs/mail-server.git", features = ["local_delivery"] }.

[soywod]

I finally found, I needed the option ("queue.outbound.next-hop".into(), "'local'".into()).