I am Facing Delayed Mail Delivery from My Domain

Mail sending delay can be attributed to sending server some extent, but receipt cannot be. Receipt is purely based on when the mail is sent from the remote server.

There is only one way that a mail receipt can be delayed at receipt side. That is if a mail box is full, then the remote server will be allowed to deliver mail only when the mail is cleared or has more space to receive that mail. Other than this, there could no issue from receipt server side.