GMS has returned an error to a remote server’s EXPN command because GMS has been configured to only accept messages encrypted by the secure socket layer (SSL ) from this remote system. No communication between the remote server/client and GMS will be possible until the remote server correctly negotiates a secure connection. GMS uses the standard secure transport specified in RFC2487 to ensure compatibility with other messaging servers.
In this case, session Undefined is processing a connection from Undefined. The remote server gave the SMTP command
GMS rejected the command with
530 Must issue a STARTTLS command first.
To resolve this problem, make sure that
- GMS has the correct certificate installed;
- the remote server or client conforms to the SSL or STARTTLS standard; and
- the remote server or client is correctly configured.
- What are the benefits of protocol level encryption?
- How do I set up Secure SMTP (STARTTLS)?
- How do I contact the owner of a client?
- Can I provide secure access to email?
- How do alerts work?
- What is the SMTP MAIL clause?
- What is the SMTP EXPN command?
- What is SMTP Response Code Theory?
- Which Type of SSL Certificate should I choose?
- How do I contact the owner of a remote server?
Keywords:STARTTLS SSL EXPN RFC2487 encryption security anti-snooping secure 8110