properly migrate pop and nntp servers from 4.x that were not on the default ports (110 and 119, respectively). also, set the default port pref to be -1, so that if we don't set the port, it gets set to -1.
properly migrate pop and nntp servers from 4.x that were not on the default ports (110 and 119, respectively). also, set the default port pref to be -1, so that if we don't set the port, it gets set to -1.