Apple mail the server rejected one of the recipients addresses

The frustrating error!

When Apple Mail says "The server rejected one of the recipients' addresses," it usually means that the email address you're trying to send to is invalid, doesn't exist, or is blocked by the recipient's email server.

Here are some possible reasons and solutions:

  1. Typo or incorrect email address: Double-check the email address you're trying to send to. Make sure it's correct and free of typos.
  2. Email address doesn't exist: The recipient's email address might not exist or be inactive. Try contacting the recipient directly to confirm their email address.
  3. Recipient's email server is down or experiencing issues: The recipient's email server might be experiencing technical difficulties, which can cause the rejection. Try sending the email later or contacting the recipient's IT department.
  4. Recipient's email account is full or over quota: If the recipient's email account is full or over quota, the email server might reject the email. Ask the recipient to free up space in their inbox or upgrade their email plan.
  5. Spam filter or firewall issues: The recipient's email server might have a spam filter or firewall that's blocking your email. Try sending a test email to the recipient's email address to see if it's a specific issue with your email or a general problem.
  6. Domain or email server issues: The domain or email server of the recipient's email address might be experiencing issues. Try contacting the recipient's IT department or email provider to resolve the issue.

To troubleshoot the issue, you can try the following:

  1. Check the email address you're trying to send to for any typos or errors.
  2. Try sending a test email to the recipient's email address to see if it's a specific issue with your email or a general problem.
  3. Contact the recipient directly to confirm their email address and ask if they're experiencing any issues with their email account.
  4. Check the recipient's email server status to see if it's experiencing any outages or issues.
  5. If you're still having trouble, try sending the email from a different email account or using a different email client.

I hope this helps you resolve the issue!