Firstly, my apologies as this issue appear to be an old topic.  However, I am unable find a solution in the discussion threads.

Story:

I recently tried to leave Gmail (after using it for about a decade) and give MS email a try just to reduce my dependence on Google products and make it harder to them to target me with ads.  I set up my Gmail account to forward emails to a Live.com account that I have.

Before I even sent my first email I am blocked "due to unusual activity".  I can still receive emails but I can't send emails.

I am asked to verify my account by providing MS with my cell phone number.  I have read their privacy policy but I feel strongly about giving my cell number to MS if I don't have to.  I suspect they will store this on a database and run lots of analytics to better target me with ads.

I contacted support.microsoft.com and I have a support call open but the Escalation Agent said everything is working fine. I have send the MS support screen dumps of the error message and this has been going on for a week.

Any ideas?  I am strongly thinking of closing down this account and move to another email provider.