Chatmail messages are bounced by iCloud mail (sometimes)

[Amzd]

• Operating System (Linux/Mac/Windows/iOS/Android): iOS 16
• Delta Chat Version: v1.48.1
• Expected behavior: emails can be sent to iCloud email provider
• Actual behavior: sometimes emails are bounced with host mx02.mail.icloud.com[17.57.155.25] said: 554 5.7.1 [CS01] Message rejected due to local policy. Please visit https://support.apple.com/en-us/HT204137 (in reply to end of DATA command)
• Steps to reproduce the problem: send 5 emails to an icloud email. (If you don't have one, use chat@casperzandbergen.nl) See some of them get bounced.
• Screenshots:
• Logs:

  
  Sent: 2024.10.17 15:28:19 by Me (xahr6kev1@nine.testrun.org)
  State: Failed, Encrypted
  Error: Undelivered Mail Returned to Sender – This is the mail system at host nine.testrun.org.

I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.

For further assistance, please send mail to postmaster.

If you do so, please include this problem report. You can delete your own text from the attached returned message.

               The mail system

chat@casperzandbergen.nl: host mx02.mail.icloud.com[17.57.155.25] said: 554 5.7.1 [CS01] Message rejected due to local policy. Please visit https://support.apple.com/en-us/HT204137 (in reply to end of DATA command) Message-ID: 8ykRs2Ko7ibw834AQ6rI4ACV@localhost </INBOX/;UID=77>

I contacted Apple support about this (because I pay for the email provider and am not receiving emails) and they said that it's probably the headers that are sent but they can't fix it on the consumer side and that I should contact icloudadmin@apple.com and sync with them why exactly these mails are bounced. I hoped someone with more knowledge of how chatmail (or email in general) works could contact them to pin point why chatmail is sometimes not received by iCloud mail.

[hpk42]

No answer yet from icloudadmin ? Can you paste/screenshot the mail to them?

[missytake]

here, I also took sysadmin@testrun.org in CC, the chat is called [sysadmin] Undelivered Mail Returned to Sender:

Hello 🙂

one of our users (the mail server is https://nine.testrun.org/) reports that they can't send legitimate messages to iCloud users. They used the Delta Chat app as MUA. I managed to reproduce the problem, here an attached mailer daemon error (including the rejected message) and a screenshot of how it looks in the app. Can you look into the matter?

Best regards,

Nami from the testrun.org team