question: Unable to send email while connected to VPN
answer: 
  If you can’t send emails while connected to the VPN, ExpressVPN might have blocked your email client’s TCP port 25, which is used to transfer emails between mail servers.
  
  To resolve the issue, adjust your settings in the ExpressVPN app as follows:
  
  Allow access to the local network
  Exclude your email app from connecting to the VPN
  1. Allow access to the local network
  
  Go to ≡ > Options/Preferences > General. Check the box for Allow access to devices on the local network (such as printers or file servers).
  
  2. Exclude your email app from connecting to the VPN