expressionsgreetings
I'm talking with my clients on a daily basis, mostly via conference calls (only voice calls, without video).
Is it OK to take leave of them by saying "see you tomorrow" at the end of the meeting, although we never see each other? Is there maybe a more appropriate greeting for this situation, like "talk to you tomorrow"?
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.
"How do you do" is a simple greeting or salutation.
how do you do — a polite greeting that you can use when first introduced to someone
A more modern variant would be, "How are you?" or "Nice to meet you."
As for usage trends, NGrams can give us a small hint at when it began to phase out of style. Note the decline between 1900 and 1920:
Best Answer
It's perfectly fine to use face-to-face or telephone metaphors when referring to online interactions. We haven't coined new terms for all the modern modes of interaction on the Internet. Much computer-related terminology is based on metaphors from the physical world, e.g. "desktops".
I think most people would say "talk to you tomorrow", since it accurately describes what they're doing in a voice-only call. But in informal conversation, when the context makes the mode of interaction clear, and it's not necessarily visual, you can use other words like "see you" (as Cascabel said in a comment, it's common for blind people to use the phrase "see you" even though they're incapable of doing it literally).
If you need to be specific, you can say things like "skype you tomorrow" -- some dictionaries have added this as a generic verb, e.g. Lexico
I've also heard people use "Facetime" as a verb.