Not receiving email notification on assign

We are using the free version of You Track in the cloud 4.0. When I assign an issue to somebody the assignee does not receive email notification.

Is there anything in the settings that I may have changed that could cause that ?

I reset both workflow and notification templates to defaults.

When I try to send an email from Administration->Settings I do receive the test email. I also receive a test email when trying to send it from user's profile page.

I tried setting user's email to both @ourcompany.com or @gmail.com but that did not help either.

When I originally set up the youtrack project I did receive [YouTrack, Assigned emails]

Any suggestions ?