[bug]: SMTP relay sent to wrong domain

[europacafe]

What happened?

Send a mail to my yahoo, gmail, and outlook accounts in one mail. The mail reached my gmail and outlook mail without problem, but my yahoo mail did not receive it (either in inbox or spam), instead my gmail received the same mail twice, one in its inbox, the other one in its spam box.

I found this incident two times.

If I sent a mail to only my yahoo mail, it reached its inbox/spam box every time.

FYI, I use "brevo" smtp relay free tier service.

How can we reproduce the problem?

I can reproduce the problem by doing the following steps: set up remote servers set routing to the remote servers send a mail to yahoo mail and gmail

Version

v0.7.x

What database are you using?

RocksDB

What blob storage are you using?

RocksDB

Where is your directory located?

Internal

What operating system are you using?

Docker

Relevant log output

Thu, 25 Apr 2024 12:31:53   
INFO    
smtp::outbound::delivery: Delivery completed. context="queue" event="completed"
Thu, 25 Apr 2024 12:31:52   
INFO    
smtp::outbound::session: context="rcpt" event="delivered" rcpt="xxxx@yahoo.com" mx="smtp-relay.brevo.com" response=Delivered: Code: 250, Enhanced code: 2.0.0, Message: I'll make sure <xxxx@yahoo.com> gets this
Thu, 25 Apr 2024 12:31:51   
INFO    
smtp::outbound::session: context="rcpt" event="delivered" rcpt="xxxx@outlook.com" mx="smtp-relay.brevo.com" response=Delivered: Code: 250, Enhanced code: 2.0.0, Message: I'll make sure <xxxx@outlook.com> gets this
Thu, 25 Apr 2024 12:31:50   
INFO    
smtp::outbound::session: context="rcpt" event="delivered" rcpt="xxxx@gmail.com" mx="smtp-relay.brevo.com" response=Delivered: Code: 250, Enhanced code: 2.0.0, Message: I'll make sure <xxxx@gmail.com> gets this
Thu, 25 Apr 2024 12:31:48   
INFO    
common::listener::listen: context="tls" event="handshake" version=TLSv1_3 cipher=TLS13_AES_256_GCM_SHA384
Thu, 25 Apr 2024 12:31:48   
INFO    
smtp::queue::spool: Message queued for delivery. context="queue" event="scheduled" id=171427723762208820 from="cxxxx@mydomain.com" nrcpts=3 size=1659

Code of Conduct

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[europacafe]

my sent box

[mdecimus]

Please provide your next-hop configuration settings.

[europacafe]

I set it with Admin GUI

Remote Hosts

[puRe1337]

I have also noticed that if you enter e.g. 'relay' under 'Outbound -> Routing -> Next hop', no more mails can be received (if the relay server needs sender authentication), as these are also sent to the relay server. Is this intended?

[mdecimus]

This looks like an issue with Brevo, if you look at the logs you provided all three messages were delivered to Brevo:

smtp::outbound::session: context="rcpt" event="delivered" rcpt="xxxx@yahoo.com" mx="smtp-relay.brevo.com" response=Delivered: Code: 250, Enhanced code: 2.0.0, Message: I'll make sure <xxxx@yahoo.com> gets this
Thu, 25 Apr 2024 12:31:51   
INFO    
smtp::outbound::session: context="rcpt" event="delivered" rcpt="xxxx@outlook.com" mx="smtp-relay.brevo.com" response=Delivered: Code: 250, Enhanced code: 2.0.0, Message: I'll make sure <xxxx@outlook.com> gets this
Thu, 25 Apr 2024 12:31:50   
INFO    
smtp::outbound::session: context="rcpt" event="delivered" rcpt="xxxx@gmail.com" mx="smtp-relay.brevo.com" response=Delivered: Code: 250, Enhanced code: 2.0.0, Message: I'll make sure <xxxx@gmail.com> gets this
Thu, 25 Apr 2024 12:31:48   
INFO    

It is Brevo's responsibility to deliver the message to the right account.

[alucryd]

@puRe1337 Noticing the same thing here, did you find a way around it?

[mdecimus]

This is because you probably removed the rule routing local messages, try with this:

[queue.outbound]
next-hop = [ { if = "is_local_domain('', rcpt_domain)", then = "'local'" }, 
             { else = "'relay'" } ]

[PaddyPat]

could you post a hint, hotwo make a next-hop check to use only brevo/sendinblue only, if recipient is hotmail or microsoft or google (use relay only for special recipients)? like postfix: transport: /.*@hotmail.*/i relay:[smtp-relay.sendinblue.com]:587

[europacafe]

I believe you can add another "if" expression to the Next-Hop for special recipients. See the example here: https://stalw.art/docs/configuration/expressions/overview it could be at the "Next-Hop" expression, add another if after if "is_local_domain"

[PaddyPat]

thx but it doesn't work.. I cant save this expression Invalid variable or function name "rcpt"

[europacafe]

Have you tried as below? (if) is_local_domain('*', rcpt_domain) ==> 'local' (if) recipients = "xxx@gmail.com" || "yyy@hotmail.com" ==> 'sendinbluerouteid' (else) 'false'

When using relay smtp, please don't forget to disable DANE and MTA-STS

[PaddyPat]

Sorry, with your string it sends all mails to relay, not only mails to address or domain x …

[europacafe]

(if) recipients = "xxx@gmail.com" || "yyy@hotmail.com" ==> 'sendinbluerouteid'

sorry you need parenthesis (if) recipients = ('xxx@gmail.com' || 'yyy@hotmail.com') ==> 'sendinbluerouteid' if you want the whole domain (if) rcpt_domain = ('gmail.com' || 'hotmail.com') ==>'sendinbluerouteid'

for 'recipients' variable, according to the online documentation, it should accept an array, e.g. ['xxx@gmail.com', 'yyy@hotmail.com'], but it doesn't work even if it passes the config validation and can be saved and reloaded.

[PaddyPat]

Thanks, this was the mistake 👍