Free Trial Buy License

← Knowledge Base

"550 5.5.1 user unknown" or "503 5.5.2 need Rcpt command" from Exchange

Exchange 2007 / 2010 / 2013

  • Verify your domain is listed in Accepted Domains (Organization Configuration > Hub Transport).
  • Verify users have the correct email address assigned in Active Directory.
  • For distribution groups: run Set-DistributionGroup GROUPNAME -RequireSenderAuthenticationEnabled $False to allow external senders.

Exchange 2003

Disable recipient filtering in Exchange System Manager under Global Settings > Message Delivery > Recipient Filtering.

Screenshots — step by step

Check these configuration pages in the Exchange System Manager
Check these configuration pages in the Exchange System Manager
On the "Recipient Filtering" page the option should be turned off (ensure that "Filter recipients..." is not activated)
On the "Recipient Filtering" page the option should be turned off (ensure that "Filter recipients..." is not activated)
Ensure also that the "Drop connection if address matches filter" option is turned off on the "Sender Filtering" page
Ensure also that the "Drop connection if address matches filter" option is turned off on the "Sender Filtering" page
The connection filter configuration should be empty
The connection filter configuration should be empty
Intelligent Message Filtering tab
Intelligent Message Filtering tab

Need more help? Contact support