Verifying custom domain Outlook account via SMS fails. No verification code is received after a day.

Hi,

I registered custom domain with http://domains.live.com and made all necessary DNS/MX/TXT changes at my registrant. After verification process vas complete it activated my custom domain account and allowed me to crete Emails. So I created for now 2 Email accounts and was able to sign in into these accounts. More I am able to receive Email just fine. But when I try to send an Email it shows following message:

Please verify your account. We've noticed some unusual activity in your Outlook account. To help protect you, we've temporarily blocked your account.

So I clicked the button Verify which takes me to https://sms.live.com website. There I've entered my US phone number and clicked Next to get the Verification code. It has been a day and I still got nothing. Tried to remove and then add number again without success. And when I click resend verification code I get following error as well: Sorry, we can't do this right now. Please try again later.

So at this point I am stuck and not sure what to do?

Thanks!