SMTP push was useful to me then
For a couple of years before I got cable broadband and started renting a cloud server, Demon's Internet service enabled me to operate automated mail discussion list distributions which propagated 4 x daily using a crontab based dialup routine together with Linux, Sendmail and Majordomo. In order to avoid spending too much on the then per minute dialup charges I had a forced timeout after 20 minutes or so. This worked fine until one of my mailing list users tried sending a 9MB attachment to one of my lists, which had the effect similar to repeatedly trying to get an elephant through a revolving door blocking other traffic.
Another problem was the 'demonic' domain name, solved by registering the driveout account which formed the subdomain driveout.demon.co.uk .