Did not issue mail/expn/vrfy/etrn during connection to mta

A technical issue!

The error message "did not issue mail/expn/vrfy/etrn during connection to MTA" typically indicates that a mail server (MTA - Mail Transfer Agent) did not respond with the expected commands during a connection attempt.

Here's a breakdown of the commands mentioned:

1. MAIL: This command is used to initiate a mail transaction. The MTA should respond with a 220 code, indicating that it's ready to receive mail.
2. EXPN: This command is used to expand a mailing list. The MTA should respond with a list of email addresses.
3. VRFY: This command is used to verify an email address. The MTA should respond with a 250 code and the email address if it's valid.
4. ETRN: This command is used to request a transfer of mail. The MTA should respond with a 250 code if it's willing to accept the transfer.

If the MTA doesn't respond with these commands, it may indicate one of the following issues:

• The MTA is not configured to respond to these commands.
• The MTA is not running or is experiencing issues.
• The connection to the MTA is being blocked or refused.
• There's a network issue preventing the connection from being established.

To troubleshoot this issue, you can try the following:

1. Check the MTA's configuration and logs to ensure it's configured to respond to these commands.
2. Verify that the MTA is running and reachable.
3. Check the network connection and ensure it's not being blocked or refused.
4. Try connecting to the MTA using a different client or tool to see if the issue is specific to the client or the MTA.

If you're still having trouble, feel free to provide more details about your setup and the error message you're seeing, and I'll do my best to help you troubleshoot the issue!