IP Blacklisted for Receiving Email using VPN

This is more of an observation -- not a question.  I use Thunderbird (smtp) to get my emails.  A few days ago, I turned on VPN, and it said my IP was "blacklisted", and wouldn't let me access my email.  I turned off VPN, and it started working again.  This was on my PC.  I was using Norton VPN (I use Norton antivirus).  So much for Norton.  (I have no idea what IP Norton was using to connect with).