You mean "Message in a Bottle". A fine episode to be sure, I thought the way the two EMH's played off eachother was great, and I feel the idea was more original than Timeless which was the usual time travel hijinks with a twist.
Oops. Message, not ship...my mistake.
And yes, time travel stories aren't uncommon in Trek, but IMO Timeless went above and beyond, and I would say it's one of, if not, my favorite time travel story Trek has ever done.
And as exodus pointed out, this episode took two characters who were normally a little dull (or in Kim's case just plain annoying) and turned them into rich and interesting people who you really cared about and could sympathize with.