A good alternative is changing the name of the trade he hasn't finished yet to "BEWARE: 1 month no communication!" or something like that.
I wouldn't say that it is an alternative per se, because not everybody is guaranteed to go look at his trades. I do agree that it is a good thing to do in addition though. But in my case, I plan on just canceling the trade, so that won't really do anything, and it really only works if you want to have a useless trade sitting there for quite a while.