ERPNext email alert not working

I just recently started using ERPNext, i set up a vehicle request doctype in such a way that the requester gets an email alert as soon as the status field in the request is changed, i also set up at the set value after sent feature to make sure the alert doctype was run , but yet i got no alert!,
find screenshots below.
Any assistance will be appreaciated.

error message from the email queue doctype

It turns out the issue came from the fact that i was using a yahoo email as outgoing email address