Originally Posted by
Gertrude the Wombat
Really it's daft to block you from using port 25 to send email via your own server which requires authentication but that's what some WiFi ISPs seem to do.
You assume wrong. The reason they block port 25 is because that's the traditional SMTP server-to-server port which spambots use to brute-force send to other SMTP servers, that don't require authentication for company-to-company email traffic (for obvious reasons). If they allowed that to happen, their own IP address ranges get marked as spamming and that negatively affects the reputation for the legitimate email traffic.
i.e. it's not as daft as you think.