AspEmail generates the following error when trying to send a message:550 Relaying Denied
Other variations of this error for different SMTP implementations include:
550 Unable to relay for email address
550 Relaying is prohibited
550 This address is not allowed
550 not local host somehost.com , not a gateway
571 email address we do not relay
553 sorry, that domain isn't in my list of allowed rcpthosts (#5.7.1)
These errors come directly from your SMTP server. They mean that the SMTP server you are using is configured to reject messages sent to outside email addresses and originating from unauthorized IP addresses or users.The purpose of such a restriction is to block spammers from using this server to send unsolicited email.
To fix the error, you must have your system administrator enable relaying at least for certain IP addresses, or certain authenticated users.
To enable relaying in the Microsoft SMTP services, right-click on the Default SMTP Virtual Server under Internet Information Services Manager, select the Access tab, and click on the Relay button.
If relaying is only allowed for authenticated users, you should take advantage of AspEmail's support for SMTP authentication via the properties Mail.Username and Mail.Password . Check with the AspEmail User Manual for more information.