If you talk with someone on the phone before (or instead of) meeting them in person, it would sound odd to say "nice to meet you." Instead, you would say "It was nice talking with you," and possibly add that you look forward to meeting them (or hope to meet them, at least) in person.
Similarly, an exchange of written correspondence doesn't constitute a meeting either. It would be laughable to use "Nice to meet you" as the close of a letter.
I personally avoid using "meet" to describe an internet encounter, whether in email or chat, even though my fingers often want to type just that. Such an encounter is a kind of meeting, as @kiamlaluno notes in his comment, but it seems so much less than a real meeting that it feels awkward to call it that. Nevertheless, this is the Internet, and what may hold for one medium may not hold for another. I would say that if you have a lengthy, soul-baring chat session with someone via the Web you might well say it was nice to meet that person, since you did exchange more than just a few words. But that would be a figurative usage, and it could apply to a similarly lengthy phone call.
As a final note, people talk about others they have "met online" all the time. So I think this argues for at least considering online encounters as legitimate "meetings" — and if they can be called meetings, I suppose it would not be too surprising to hear "Nice to meet you" in an email. But I think it still involves more than the exchange of a few words.
Perhaps
pushover - a person who is easy to overcome or influence:
Colonel Moore was benevolent but no pushover
or
patsy - a person who is easily taken advantage of, especially by being cheated or blamed for something
or
soft touch - (informal) a person easily persuaded or imposed on, esp to lend money
Of the three, the last is probably the most positive (at least in US usage). The other two suggest gullibility.
Best Answer
While it does sound a little formal, you could "say":
... and so on.
That said, I don't particularly see anything wrong with using meet. You are simply meeting online which is well-established terminology. The word hear is also used often.