problems sending emails when abroad

[#1]

This week I am in Netherlands:

I can send email over (Plusnet roaming) 4G from my phone. I can send email over wifi from the same phone

My laptop uses Outlook 2016, and in the UK, from home, or other places, I can send emails. However, I seem unable to SEND emails from here in NL! When I try to send, I get an error 0x800CCC0F: "The connection to the server was interrupted. If this problem continues, contact your server administrator or internet service provider (ISP)"

Anyone else seen this?

[#2]

And a bit of extra info:

If I tether my laptop to my phone, and thus send via the 4g, it sends just fine!

I should add that, on the wifi, I can RECEIVE my emails just fine!

[#3]

That is a odd issue.

What port are you using to connect to relay.plus.net?

If it's 25 ig may be worth trying 587 and vice-versa

[#4]

Some network providers block access to remote relays on port 25. To be perdantic for email client message submission port 587 (not 25) should be used.

Port 25 is allocated for MTA to MTA relay.

[#5]

My email is actually set up to use port 587, but I also tried port 25. I have a feeling that they may have done a fairly tight lockdown here.... I don't know why they would do so though, I mean what the purpose.

[#6]

Hi Paul, 

Do you have your email client set up to use S