Have you tried using Port 465 instead? 

I assumed you asked question about your Telus email account. This forum is for Koodo customer, The Telus community might be a better source for help as Koodo doesn’t provide Telus.net service.

Anyway, regarding the telus.net email, I got some experience with it. Telus asked customer to move the data to Google. have you done that? if so, you would have to change the email server to smtp.gmail.com. More detail here https://www.telus.com/en/bc/support/article/telus-email-as-alternative-application

Hope it helps.

@MilkyWay thanks for that, but yes I did try 465 too. Then I think you don't use Starttls, you use SSL/TLS. Did I get that right?

@Dinh I am a Koodo customer, and was told many years ago to use the Telus SMTP server.  It has worked fine for years. Now I have problems, and maybe it's just a username/password issue. That in itself seems to  be difficult to fix. Are you saying that Telus has dropped email support?

Yes, that is correct. It is for SSL. 

@Richard Leir  I am still not sure if I understand. Koodo doesn't provide email service. 

If you are using telus.net email you should have received an email from Telus about google migration. The link above should have parameters for your email settings.