Forwarding email to gmail stuck in queue

Hi, I have hosted a website mydomain.com. and I have created a mail forwarder on it. from user@mydomain.com to user@gmail.com. So My issue is, all mail which are coming to user@mydomain.com the have to delivered on user@gmail.com. But the are stucking in Mail Queue of server. mostly social media notifications are stuck in mail queue of server.