This period usually lasts about three weeks and can make communications go haywire. It's not a good time to sign contracts, because they usually have to be redone. Mail and messages get delayed and sidetracked. Names get written down wrong, numbers get transposed. Any major purchases made during this time usually has some irritating minor problem.
Writing takes more effort.
If you really take the time to focus and double check your work, you can avoid much of the problems which are associated with Mercury in retrograde. It's a great time to redo, reorganize and clean up your projects. It's also a time to go within for some deep subjective thinking. If you can delay signing the papers until Mercury turns direct, you'll probably find new developments arise which can be beneficial. Of course planets don't actually move backwards, but when they slow down, they appear that way when viewed from Earth.