This error message indicates that your email was rejected by the recipient's server after transmission (phpmailer, jenkins). This often signifies spam filtering or Sender Policy Framework (SPF) configuration issues.

What Triggers This Error?

Two primary reasons can cause this error:

1. Recipient's Spam Filter: The recipient's email server's spam filter might flag your message as spam due to content, sender reputation, or other factors.
2. SPF Record Misconfiguration: The sender's domain's SPF record might be configured incorrectly, causing the recipient's server to reject the email due to unauthorized sending.

Resolving "SMTP Error from Remote Mail Server After End of Data"

Here's how to address this error:

1. Contact Recipient: The sender can reach out to the recipient to inquire if their email address is configured to accept emails from the sender's domain and check their spam filters for any blocked entries.
2. Review Email Content: Analyze the email content for potential spam triggers like excessive attachments, promotional language, or misleading information. Revise the content if necessary.
3. Verify SPF Record: Ensure the sender's domain's SPF record is configured correctly to authorize the email server used for sending.
4. Adhere to Email Best Practices: Always follow email best practices to maintain a good sender reputation and avoid sending content that might be flagged as spam.

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