553 mail error

The infamous "553" error!

The "553" error is a common SMTP error code that indicates a problem with the recipient's email address. Here are some possible causes and solutions:

Error message: "553 Sorry, that domain isn't in my list of allowed rcpthosts (#5.3.7)"

Possible causes:

1. Invalid or non-existent domain: The recipient's email address contains a domain that doesn't exist or is not recognized by the sending server.
2. Domain not allowed: The sending server has a list of allowed domains (rcpthosts) and the recipient's domain is not on that list.
3. Email address syntax error: The recipient's email address contains invalid characters or is not in the correct format.

Solutions:

1. Check the recipient's email address: Verify that the recipient's email address is correct and valid. Make sure it's in the correct format (e.g., [email protected]).
2. Check the sending server's rcpthosts list: If the sending server has a list of allowed domains, check if the recipient's domain is on that list. If not, you may need to add it or use a different sending server.
3. Use a different sending server: If the sending server is blocking the email due to a domain not being allowed, try using a different sending server that allows the domain.
4. Contact the recipient's email administrator: If the error persists, contact the recipient's email administrator to see if there are any issues with their email setup or if they have any specific requirements for sending emails to their domain.

Remember to always check the error message and the recipient's email address to determine the cause of the error and take the appropriate action.