I saw that there are also other questions related to mines but the solution provided or the workaround has not helped me. Below you will find more details.

1. I've checked the Safe Senders List and it contains the senders mail.

2. I've disabled the forwarding

3. I have no aliases

4. No junk filter

I asked some people to send me emails from different domains such as Yahoo, Gmail and corporate ones with no luck. From their side they did not get any bounce mails with any notification. 

Services seem to run successfully (green tick ) but on the other hand I have not received any mail. In addition there is no notification about 'no free space' so this doesn't seem as a problem. 

Can anyone help?

Regards

Spiros

P.S I have checked the option for notification in case there is a response but as you can understand I won't get any :):) Hope I do :)