Mail delivery failed: returning message to sender

I am looking for a freelancer who can help me resolve an issue with my mail delivery.

Email Service: Exim mail server

Issue: The problem is occurring with specific recipients.

Error Message:
helocheck @ abuseat.org
SMTP error from remote mail server after RCPT TO abuseat.org
550 *** The HELO for IP address 149.56.69.65 was 'mail.townhousesdubainew.net' (valid syntax) ***
host mail.abuseat.org [54.93.50.35]
Action: failed
Final-Recipient: rfc822; helocheck @ abuseat.org
Status: 5.0.0
Remote-MTA: dns; mail.abuseat.org
Diagnostic-Code: smtp; 550 *** The HELO for IP address 149.56.69.65 was 'mail.townhousesdubainew.net' (valid syntax) ***

Skills and Experience:
- Experience with Exim mail server
- Knowledge of troubleshooting mail delivery issues
- Familiarity with diagnosing and resolving error messages
- Ability to work with specific recipients to resolve the issue