POSTFIX: how to determine how many connections are currently active

I'm running postfix on a mail server which is used by a couple hundered users. One user is getting "Connection Interrupted" errors in Outlook when attempting to send. I have not had reports of this problem from anyone else.

Closing/reopening Outlook does not solve the problem. Restarting Postfix daemon on my end solves the problem. It is as if the connections are not being closed cleanly, thus triggering the smtpd_client_connection_count_limit which is set to 8. Possibly the user's virus scanner is grabbing the SMTP traffic and failing to terminate the session properly...

Is there any way I can see a list of current "open connections" to the postfix service, along with the source IP address and possibly the username used to authenticate? I want to see if this user's connection count increases over time.

I realise I can use netstat -pt | grep smptd to find open connections to the smtpd daemon and show the remote IP address. I'm looking for more details which may include username, as there are several users coming into our server from the same IP address as the problem user.

Appreciate any info.

Thanks