Outlook.com - forwarding emails ... no Save button

Indeed!

This is the most stupid thing I came across in a very very long time. Having to add a phone number to get a save button. Don't you think this is more than ridiculous?

This solved my problem. Thanks. The Save button appears after I have added a phone number to my account!

This is it!

I actually had to add a phone number to the 2 step verification part of my* account. I suggest whoever has this problem to try and add new methods of authentication. Outlook doesn't tell you why you can't add forwarding there but, at leat in my case, it had to do with adding a phone number to the Account Security section of my outlook (web).

I'm not 100% sure but I have a strong feeling it would have to do with the security info of your own outlook account in almost all cases since, according to what I have read in this forum it is not a cache problem.

I habe eben adding a Phone nun er and IT did Not work.

Outlook regulary also removes the Button and forward again, even of you solve the Problem.

I solve IT in August, it worked 1 week, then its Not working again.

Their Reputation Thing sucks

It seems to be a reputation thing and to stop it being used as a Spam relay.
Adding a mobile improves the reputation and so very much less likely to be used for such malicious activity.