A thread very similar to this already exists on MTG, but some may have missed it.
This method allows you to contact the requester in question BEFORE you submit a hit for them. It is a great way to ask for further clarification or to let them know about a bug.
To be specific, you need to acquire the requester's ID, and then put it after the '=' above. A common way to get their ID is by using Turkopticon.
In the case above, the requester I am 'trying' to contact is Jon Brelig. The ID is in bold to make it easier to understand.