Selecting the "Send an email" option in the Defender Management Portal Token Deployment system, and then an error is returned:
"Sorry, there was a problem sending an e-mail. Please try again later. "
Also, the Token Deployment configuration page may return a similar error:
"Sorry, there was a problem sending an e-mail. Please try again later. Service not available, closing transmission channel. The server response was: 4.3.2 Service not available"
This indicates an issue between the Defender server and the email server.
Can the Defender server ping the email server by IP? By name (rule out DNS issue)?
Is a telnet test from the Defender server to the email server on the required port (port 25 is the standard SMTP port) successful?
Ensure that connectivitiy between Defender and the mail server is successful.