Monit: SMTP: Mailserver response error -- 550 Sender -Verification failed for <[e-mail]>

[Terish]

Instead of from: [e-mail]

Monit sends emails from monit@$hostand that is causing SMTP 550 error

set mail-format {
    from: [e-mail]

Using Monit 5.32.0 as addon to IPFire (https://www.ipfire.org/) I configured monitrc as fiollows

SET MAILSERVER
    smtp.mailserver.com
    PORT 465
    USERNAME [e-mail]
    PASSWORD Pa$$
    using tls

SET MAIL-FORMAT {
from:    Monit <[e-mail]>
subject: Monit alert on $HOST  --  $EVENT $SERVICE
message: $EVENT on the service: $SERVICE

Date:         $DATE
Action:       $ACTION
Host:         $HOST
Description:  $DESCRIPTION
}

SET ALERT [e-mail]

‌

you could substitute either of these:

from: Monit <monit@$HOST>

from: [e-mail]

they all result in the same error in system log:

SMTP: Mailserver response error -- 550-The mail server does not recognize monit@ ipfire.lan as a valid sender.
Alert handler failed, retry scheduled for next cycle 

P.S.

Similar error found in OPNSense - 5 years ago

https://github.com/opnsense/plugins/issues/145

[Tildeslash]

Hi,

please can you run monit in the debug mode? It’ll log SMTP session details.

1.) stop Monit

2.) start it in debug mode in foreground:

‌ monit -vI

Please collect the debug messages for SMTP and send it to us.

[Terish]

Thank you. running it in foreground

monit -vI

seems to fix the issue.

12:09:03 monit[22325]: SMTP <- 235 Authentication succeeded
12:09:03 monit[22325]: SMTP -> MAIL FROM: [e-mail]^M
12:09:04 monit[22325]: SMTP <- 250 OK
12:09:04 monit[22325]: SMTP -> RCPT TO: [e-mail]^M
12:09:04 monit[22325]: SMTP <- 250 Accepted

‌

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