Activity block and email send error

I recently bought a new laptop. After setting it up I received a suspicious activity block.

I have reset the password, performed an account recovery and updated my security information.

While I am receiving mail without issue, I am still unable to send mail. The following error report is returned automatically every time:

We weren't able to send this message, so we've put it in your Drafts folder. Before you try sending it again, you can check to see if the address is correct and that no attachments are too large.

Sadly 48 hours into the issue this setback is seriously hampering my professional productivity and personal life and so I have had to go to the dark side and get an email from the evil G-people to get on with my life.

I would hope that this can be solved so I can keep using my beloved Hotmail account properly.

Any suggestions or ideas?

Warmest regards.