Undelivered mail: 550 5.7.1 Mail rejected. (in reply to EOD command)

Probeer mijn partner te mailen. Aleen die mails worden geweigerd.

Melding:  said: 550 5.7.1 Mail rejected. (in reply to EOD command).

Ik werk met MS-Outlook en mijn partner heeft een alias, zoals ook ikzelf (van een ander hoofd-e-mailadres).

Kan iemand hier iets begrijpelijks van maken? Alvast vriendelijk dank!

In de bijlage van de postmaster lees ik: 

Reporting-MTA: dns; ewsoutbound.kpnmail.nl
Received-from-MTA: dns; smtp.kpnmail.nl (10.31.155.40)
Arrival-Date: Thu, 25 Jan 2024 19:58:33 +0100
X-Original-ID: bc9c320b-bbb3-11ee-a95f-005056abbe64

Final-Recipient: rfc822; beata.nowak@telfort.nl
Action: failed
Status: 5.7.1
Remote-MTA: dns; mx.kpnmail.nl (195.121.65.158)
Diagnostic-Code: smtp; 550 5.7.1 Mail rejected. (in reply to EOD command)
---------------------------------------------------------

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