On 18/12/2019 10:04, The Natural Philosopher wrote:
On 18/12/2019 09:31, Sn!pe wrote:
Back in the day, ISPs would commonly hijack port 25 SMTP traffic
and silently push it through their own SMTP server instead as an
anti-spam measure.Â* Even though nowadays other ports are used,
is that not still the case?

I think only BT has the power to do that. And possibly mobile operators.


BT at one time used to block TCP/25 to anywhere but their own SMTP
servers for domestic customers. Not sure if that's still the case.