TwoSeven: ... I don’t use the web client as I mainly use the app/desktop version. ...
These days, a lot of the settings are sync'ed between OWA & the Desktop / Classic application. If you create any rules in OWA, they will work in Classic. Only in Classic do you want to be aware of 'client only' rules that require Outlook Classic to run on your Desktop for the rule to apply.
neb:
This is Outlook365Web or whatever it's called, not the app, ... You can just keep blocking the same sender till the cows come home to no effect. It seems to be because it uses the display name rather than sender name or vice versa, so never recognises that a sender is blocked.
When creatign rules in Outlook, I never use the 'People > From / To' option. Like you' I've found it to not work as expected. Instead, I use the 'Keywords > Sender address includes' option which does allow wild cards. Admittedly, I don't know if it will do the double wild card that you want to do. OWA did allow me to save the rule, but YMMV.
There are only two things I like in the Outlook Classic app installed on your Desktop. I have not found these options anywhere else. One is to block country level domains (ccTLD) such as .vn or .ru. The other is to bock any emails written in a code page you don't expect emails to be in. I don't expect emails in Cyrillic, Hindi or any of the many other international character set. ASCII & Latin-1 is good enough for me.