Using Google's SMTP Server If SMTP port 25 is blocked

I have this sever I got for nearly for free but the problem is smtp port has been blocked by data center because of this providers servers are used for spam since those are very cheap.

So I talked with provider and seems port 25 won't be enable anytime soon so I need to find another way to do to site mail.

I heard you can use Google's SMTP Server to relay mail and get those into my server. I have no idea how to do it. So any one know any good guide or tutorial about it ?

Or any other method to use.