The ‘SMTP 555 error’ typically occurs on sites that send emails through an SMTP server. It indicates a syntax error in the From email address you configured.
It can occur due to incorrect spelling or missing syntax in the sender or recipient email address.
This error can also be triggered by a misconfiguration in the email client settings or by the server’s inability to recognize or process certain commands
Resolving the Error – Solution
To resolve this issue, you’ll need to review your SMTP server’s settings to ensure it is properly configured. Check for misspellings or syntax errors in the From email address.
Also, review the recipient’s email address(es) and fix any spelling or syntax errors on it.
If you’re running your own SMTP server, ensure that it’s properly configured and supports the commands your recipient’s email client uses.