gen_smtp: be notified on failed delivery message

[Frank Muller]

Thanks Marc and Leonard.

/Frank

Wed. 13 jan 2021 20:59, Leonard B <leonard.boyce@REDACTED> wrote :

> Hi Frank,
>
> There are basically 2 classes of errors.
>
> 1. Errors which are derived from the delivery process. These would include
>   a) network errors (nxdomain etc)
>   b) mailboxes not existing/disabled etc (response to RCPT TO command.
> Be aware that many servers do *not* follow the RFC and will lie)
>   c) the dreaded 'blocking' of you connection for whatever reason the
> remote server decides to use
>
> 2. 'soft bounce' errors:
>   These occur when certain servers, eg outlook, will accept an email
> for delivery, and then email you back to tell you about some type of
> error.
>   You'd need to have a server receiving mail to receive the 'soft'
> errors since they are email back to you and not part of the SMTP
> transaction.
>
> There is a 3rd class of error (Yahoo/AOL and friends):
> Their servers will say that the mailbox exists (in response to RCPT
> TO:) and then tell you a mailbox does not exist _after you send your
> DATA_.
>
> Kind regards,
> Leonard
>
> On Wed, Jan 13, 2021 at 1:31 PM Frank Muller <frank.muller.erl@REDACTED>
> wrote:
> >
> > Thanks for the pointers Marc.
> >
> > Do I need to implement the server part to check for errors? Can’t the
> gen_smtp “client” be notified in case of misspelled address (or unresolved
> domain, MX, etc.)?
> >
> > /Frank
> >
> > Wed. 13 jan 2021 10:25, Marc Worrell <marc@REDACTED> wrote :
> >>
> >> Hi Frank,
> >>
> >> Yes, gen_smtp can report failures that happen during communication with
> the remote smtp server.
> >> Will also report failures if it can’t resolve the domain or find a MX
> server.
> >>
> >> Late bounces (sent by the remote mail agent) must be handled by your
> own code.
> >>
> >> In Zotonic we have an example of handling such bounces.
> >>
> >> Check for our mail sending code (which also uses mnesia for queueing):
> >>
> >>
> https://github.com/zotonic/zotonic/blob/master/apps/zotonic_core/src/smtp/z_email_server.erl
> >>
> >> And for receiving email, including parsing and handling of bounce
> messages:
> >>
> >>
> https://github.com/zotonic/zotonic/tree/master/apps/zotonic_listen_smtp/src
> >>
> >> Cheers,
> >>
> >> Marc
> >>
> >>
> >> On 13 Jan 2021, at 09:18, Frank Muller <frank.muller.erl@REDACTED>
> wrote:
> >>
> >> Hi everyone
> >>
> >> I’m considering using gen_smtp (https://github.com/gen-smtp/gen_smtp)
> in one of my apps.
> >>
> >> Question: is there a way to be notified on failed delivery message if
> for example the destination email address was misspelled?
> >>
> >> Thanks
> >> /Frank
> >>
> >>
>
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