Yes, Telus had an open smtp relay server in the past (it is still around but no longer maintained so a huge range of newer customer IPs are now ignored/blocked from connecting) at smtp.telus.net:25 Now it mostly responds with "ESMTP server not available" if your IP is not in the dwindling list of allowed IP ranges. If anyone still uses this beware. It is going away and will likely stop working suddenly on you one day soon.
The gmail server indeed would only work if you were using the Telus provided email address or some other google hosted mail like gmail or google workspace for a custom domain name.
A workaround I have used is to sign up for smtp2go service. Their server still requires a login to use, but it allows me to at least setup a more flexible configuration on my outbound email address for a few printers. If you own your own domain name you can add some customizations to allow better reporting on the emails you send through their system if you can add some dns records. There is a free tier for low volume users, but businesses may hit the usage limit for any serious usage. For the average home user just using gmail, yahoo, hotmail/outlook etc then you would just end up connecting directly to that services outbound mail server and authenticating properly with your account.
If you have some really old and bad equipment then running your own internal mail server that accepts unencrypted, unauthenticated mail and relays it out with higher levels of encryption may be required. A virtual machine or little raspberry pi and a deep dive into setting up a linux server to run as a mail relay is likely required in that case. As time marches on the Internet seems to want everything encrypted and authenticated. No more blind trust on the email server relaying outbound mail for you.
