Anyone from SmarterTools? Email sent to local domain set to External MX servers when using incoming and outgoing gateways generates "550 Authentication is required for relay".
Scenario:
- Account1 is sending email to Account2. Both are located on local server but as a security measure domains are set to External MX servers (where main SmarterMail instance is not present among MX servers because incoming gateways are used and they are only placed in DNS zone MX configuration).
- After email sending it is being relayed from main SmarterMail instance to outgoing gateway where it checks using webservice (accoring to incoming gateway configuration emails are being verified with main SmarterMail instance using webservice).
- Webservice check is returning error "550 Authentication is required for relay".
Any suggestions how problem in presented scenario can be resolved? IMHO domains set to "External MX" should have different handling when it comes to remote delivery from incoming gateways.