Message queue not sending

Having same issue on 4.20
Tons of emails in the queue.

@dan.vasiloiu
Check your System > Log for error messages
Are any emails going out?
Has it worked in the past?

I have same issue with 4.20.
Schedule task just for emails not working suddenly.
If i restart the app it will work again for sometime and stop suddenly.
No error in log.
Is there any solution for this?

I am running 4.2, and solved this problem by:
1. I found that I had slightly incorrect settings in my email account settings.
I changed the server, (host) to the my mail server IP address.
2. Unchecked the checkbox for "Use Default Credentials".
3. I also changed the Send Email Task Sequence "Seconds (run period)" to 20 seconds.
After these steps the messages in my message queue started sending. I ran the task sequence manually.

Upgraded from 3.60 to 4.30, same problem. Tried solutions on page 5 above but no luck. No error log entries, unless I remove http:// from site url, then the log shows task running at 20 second intervals, but failing due to url mismatch.