2 ms·To some extent, they can't. (How do you verify the email without being on the wifi?)by basil-rash 8y agoTo some extent, they can't. (How do you verify the email without being on the wifi?)dzek69 8y agosome may allow popoular e-mail services (and imap/pop3 ports) traffic, while blocking the otherskees99 8y agoother captive portals let user in, ostensibly to open inbox and click the link, then kick off the net if that didn't happen within 5 minutes.