Speedy development is often worth the investment of a pawn in the opening. Examples include the Smith-Morra Gambit of the Sicilian 1.e4 c5 2.d4 cxd4 3.c3 dxc3 4.Nxc3 when White has a very promising initiative for the pawn that often brings dividends. Devotees of this line can become highly attuned to its nuances. If that is the case you have to ask yourself as Black whether taking them on in their most familiar territory is the most intelligent thing to do. You might decide it is better to avoid it than to try to refute it. Even if you like spending many an hour with opening books, there is no substitute for hours of practice playing the line over and over again – which White will of course be doing. Perhaps Smith-Morra Gamiters’ would find the Caro-Kann or the French Defence, or something else, really annoying. If so, play that against them! It is wise to get your opponent out of their familiar territory.
This is the sort of thing that can be considered if you know your opponent and you’re playing them in an over-the-board game. Of course, if someone plays a gambit against you in a correspondence game and you are allowed to use software for help, then that is a different matter. For example, silicon monsters nowadays are less impressed with the Smith-Morra than we humans are. Below is one of my own correspondence games against a line of the Smith-Morra that I would have found difficult to play against over-the-board. But, with assistance from HIARCS, I found it easier to deal with. It takes a long time, but eventually White’s initiative dissipates and then it is all about whether Black can convert the ending. The knight and pawns ending was particularly pleasant to play for Black. If you would like to play some correspondence chess online, try FICGS – The Free Internet Correspondence Games Server.