@MxyzptlkFishStix
Thank you , siteground unblocked the ports and everything is working great.
Thank you so much for the time you spent on looking for a solution to my problem
Did you get the solution …now its working ?
Hi yes, I did what MxyzptlkFishStix said and asked Si9teground to unblock the ports on serverside, once they unblocked the ports, it connected to Postmark and I have sent 10 test mails and even gmail recieved them
So thank you for your time and thnks to you I learnt a few things on the way 
scroll up a few posts to see what ports where blocked.