Can't send emails when connected to VPN

[#1]

Hello all, it is my first time here, I was just after a little advice.
I have recently started using NordVPN to allow acces to a work server at a different office which has the same ip address as my main office. When I connect to the VPN I am able to send emails but not receive. I have been advised that the SMTP port 25 is blocked through the VPN to prevent spam, so to change to 587 or 465, both of which dont work they just time out. I was wondering if anyone else had similar issues and found a solution. I don't want to have to keep connecting and reconnecting every time I require files.
Many thanks in advance
Paul

[#2]

Quote

When I connect to the VPN I am able to send emails but not receive.

Sorry, I'm confused here, that conflicts with your post title!.
Is it receiving or sending that you can't do when connecting to the VPN ?

[#3]

Assuming it's sending that doesn't work, are you able to run a command prompt window through the VPN?
If you can does
telnet relay.plus.net 587
get a response from the server? This will probably be clearing the window and showing a
220 servername smtp relay.plus.net
response.
If you get that respond
quit
to close the connection. That will confirm you can reach the relay servers so the problem is elsewhere.

[#4]

Again, making the assumptions that a) You mean sending doesn't work and b) You're trying to send from your Plusnet account it may be that your work VPN setup forces all traffic over the link to them?  Inf this is the case then you need to set your email client up for authenticated SMTP as PN (not unreasonably!) need you to logon to the outgoing mail server.
I've never understood why the PN email setup guides aren't written to suggest setting up sending authentication by default as there's no harm in using it if you are on a PN connection and it would save the confusion caused when you're elsewhere...