Issue Mail forwarded on the server in the target mailbox is delivered to the SPAM folder

[W4ru]

Server operating system version

Ubuntu 24.04.1 LTS

Plesk version and microupdate number

Plesk Obsidian 18.0.67

Introduction:
I frequently use a mailbox with several alias names and then sometimes have it forwarded to a mail address of another domain on the same Plesk server.
I also use this permanently for other domains. So far everything has been fine.

Now I register a circumstance: Messages from the Plesk forum, which are delivered to plesk@domain1.tld ( an alias to info@domain1.tld ) are also forwarded to user@domain2.tld in the mail setup.
In the roundcube of user@domain2.tld (no rules in Roundcube, sive entry in the mail directory does not exist) the notification is delivered by Plesk in SPAM.

Here is the log, which shows the process in detail:

2025-01-22 15:30:04    postfix/qmgr    removed
2025-01-22 15:30:04    postfix/pipe    to=<user@domain2.tld>, relay=plesk_virtual, delay=0.89, delays=0.81/0/0/0.08, dsn=2.0.0, status=sent (delivered via plesk_virtual service)
2025-01-22 15:30:04    postfix-local    dmarc: stderr: STOP
2025-01-22 15:30:04    dovecot            service=lda, user=user@domain2.tld, ip=[]. sieve: msgid=<d98c472f8eb4675486482d9a644bdf34@talk.plesk.com>: stored mail into mailbox 'INBOX.Spam'
2025-01-22 15:30:04    dmarc            DMARC: smtpdomain=plesk.com maildomain=plesk.com mailfrom=plesk-talk@plesk.com stamp=1737556204 ip=unknown adkim=strict aspf=relaxed p=QUARANTINE sp=UNSPECIFIED pct=100 align_dkim=fail align_spf=fail spfres=unknown dkimres=pass dmarccheck=DMARC_POLICY_QUARANTINE dmarcstatus=DEFER
2025-01-22 15:30:04    dmarc            SPF record was not found in Authentication-Results
2025-01-22 15:30:04    postfix-local    dk_check: stderr: PASS
2025-01-22 15:30:04    postfix-local    from=<SRS0=GynU=UO=plesk.com=plesk-talk@domain1.tld>, to=<user@domain2.tld>, dirname=/var/qmail/mailnames
2025-01-22 15:30:04    postfix/qmgr    from=<SRS0=GynU=UO=plesk.com=plesk-talk@domain1.tld>, size=12943, nrcpt=1 (queue active)
2025-01-22 15:30:04    amavis            (1152109-25) Passed CLEAN {AcceptedInternal}, AM.PDP-SOCK/MYNETS LOCAL [127.0.0.1] [195.214.233.100] /AM.PDP <SRS0=GynU=UO=plesk.com=plesk-talk@domain1.tld> -> <user@domain2.tld>, (ESMTPS://195.214.233.100), Queue-ID: 43F1A8582B, Message-ID: <d98c472f8eb4675486482d9a644bdf34@talk.plesk.com>, mail_id: AFaInvvlUzve, b: g2wRz-sz4, Hits: -, size: 13000, Subject: "Question - Wanted: Best practice for certificates (Lets Encrypt) two separate Plesk servers for www ", From: <plesk-talk@plesk.com>, helo=localhost, dkim_i=@domain1.tld, dkim_sd=default:domain1.tld, 746 ms
2025-01-22 15:30:03    postfix/qmgr    removed
2025-01-22 15:30:03    postfix/pipe    to=<info@domain1.tld>, orig_to=<plesk@domain1.tld>, relay=plesk_virtual, delay=1.2, delays=0.6/0/0/0.57, dsn=2.0.0, status=sent (delivered via plesk_virtual service)
2025-01-22 15:30:03    postfix/cleanup    message-id=<d98c472f8eb4675486482d9a644bdf34@talk.plesk.com>
2025-01-22 15:30:03    postfix/pickup    uid=30 from=<SRS0=GynU=UO=plesk.com=plesk-talk@domain1.tld>
2025-01-22 15:30:03    postfix-local    send message: id=S1165069 from=<SRS0=GynU=UO=plesk.com=plesk-talk@domain1.tld> to=<user@domain2.tld>
2025-01-22 15:30:03    dovecot            service=lda, user=info@domain1.tld, ip=[]. sieve: msgid=<d98c472f8eb4675486482d9a644bdf34@talk.plesk.com>: stored mail into mailbox 'INBOX'
2025-01-22 15:30:03    postfix-local    arc-sign: stderr: PASS
2025-01-22 15:30:02    postfix-local    dmarc: stderr: PASS
2025-01-22 15:30:02    postfix-local    dk_check: stderr: PASS
2025-01-22 15:30:02    dk_check        DKIM Feed: No signature
2025-01-22 15:30:02    postfix-local    from=<plesk-talk@plesk.com>, to=<info@domain1.tld>, dirname=/var/qmail/mailnames
2025-01-22 15:30:02    postfix/qmgr    from=<plesk-talk@plesk.com>, size=10213, nrcpt=1 (queue active)
2025-01-22 15:30:02    psa-pc-remote    check-quota: stderr: SKIP
2025-01-22 15:30:02    psa-pc-remote    spf: stderr: PASS
2025-01-22 15:30:02    psa-pc-remote    py-limit-out: stderr: SKIP
2025-01-22 15:30:02    psa-pc-remote    py-limit-out: stderr: INFO:__main__:No SMTP AUTH and not running in sendmail context (incoming or unrestricted outgoing mail). SKIP message.
2025-01-22 15:30:02    amavis            (1152108-25) Passed CLEAN {AcceptedInbound}, AM.PDP-SOCK [195.214.233.100] [195.214.233.100] /AM.PDP <plesk-talk@plesk.com> -> <plesk@domain1.tld>, (195.214.233.100), Queue-ID: 4326E8581A, Message-ID: <d98c472f8eb4675486482d9a644bdf34@talk.plesk.com>, mail_id: qAPhY1F9CEaa, b: g2wRz-sz4, Hits: -, size: 10196, Subject: "Question - Wanted: Best practice for certificates (Lets Encrypt) two separate Plesk servers for www ", From: <plesk-talk@plesk.com>, helo=ch.origin.talk.plesk.com, 73 ms
2025-01-22 15:30:02    postfix/cleanup    message-id=<d98c472f8eb4675486482d9a644bdf34@talk.plesk.com>
2025-01-22 15:30:02    psa-pc-remote    grey: stderr: SKIP
2025-01-22 15:30:02    grey            Remote host ch.origin.talk.plesk.com in white list
2025-01-22 15:30:02    psa-pc-remote    from=<plesk-talk@plesk.com> to=<plesk@domain1.tld>
2025-01-22 15:30:02    postfix/smtpd    client=ch.origin.talk.plesk.com[195.214.233.100]

As you can see, the message sent to plesk@ is " stored mail into mailbox 'INBOX' " while the forwarded copy is " stored mail into mailbox 'INBOX.Spam' "

Hints of the current thread here: Question - Incoming mail is stored in Junk folder I have checked all of them, there are no sive settings. The config files under /etc/dovecot/conf.d show me no anomalies.
Warden is running on the server. For other accounts there is no SPAM sorting if it is not causal based on the score.