[Konstantinos]

pawn Код:

SendMessageToAll(-1, "some tests", 1);

Everyone will receive the message except ID 1.

pawn Код:

SendMessageToAll(color, const string[], exception = INVALID_PLAYER_ID)
{
    if (exception != INVALID_PLAYER_ID)
    {
        foreach(new i : Player)
        {
            if (i != exception) SendClientMessage(i, color, string);
        }
    }
    else
    {
        foreach(new i : Player) SendClientMessage(i, color, string);
    }
}