365 email forwarding

[technodup]

I have a MS365 account for email, and want to forward certain incoming emails to another address. Should be simple, and it was for a week or so but they're now being bounced back as my account doesn't allow external forwarding. I've dug around a bit and found my way to the setting in MS365 Defender to allow forwarding, but to save the change it says I need to make some other change which requires code and I haven't a clue...

How are people forwarding emails these days?