For instance, say that I text someone "I promise I'll do X." Does that have the same status as if I said out loud the same thing?
The same question can be asked with respect to Shevuos (as in oaths, not the holiday). If someone says "Swear to me that X happened," for instance, and you text him "Amen" (this exchange is cited in the third perek of Maseches Shevuos as being a form of an oath), do I have to bring an Oleh v'Yoreid if it's false and meets the various criteria brought down in Shevuos?
One other possible nafka minah: one could ask regarding Hein Tzedek (BM 49a), the obligation to keep one's word, even if not phrased in terms of a neder.
WHAT THIS IS NOT
Just to clear things up before anyone brings it up.
This question is not applicable to Lashon Hara, which just requires spreading the rumor, regardless of how it's done. At the moment I don't have the source for this claim, though I have heard it many times from my Rebbeim; if someone could provide a source, that would be great. I could make a chiluk between this and the above cases, though, where the issue is the speech, not the bad name.
This question is also dissimilar to halachos such as Virtual Kaddish or Answering Amein on the phone or even Havdalah on the phone in which the question is on the listener. My question is whether the texter has fulfilled any form of speech.
Also related, as this is about texting or emailing, this is not similar to התראה by phone which involves actual speech.
I'm also aware of this question about chat contracts, which is more of an issue of the legal status of the contract, not about whether it's a type of speech.
Finally, there is also this question about Hamapil which is highly related and I know someone's going to call duplicate. So I'd like to emphasize that my question is much, much broader. Maybe, for instance, that, which is only a d'Rabbanan, might be permissible, whereas by Nedarim, which is d'Oraisa, may require us to be stringent and force him to abide by his vow.
Is texting, essentially a written form of spoken conversation that hardly ever follows proper grammar (or spelling) considered speaking across Halacha, or in limited circumstance, or nowhere at all?
As a springboard, this discussion about whether digital text is considered written text l'halacha may be relevant.