There are different platforms of communications, and some people would seem unfamiliar with how each method is to be used. This page will hopefully provide some clarification, and people reading this page will go to understanding how to use the methods available.
SMS, and MMS is also know as text messaging. A general rule of thumb is that SMS is limited to 140 characters – however many SMS clients will break and merge longer messages up without your intervention. SMS is good to provide small bits of information. For example, if someone wanted a telephone number, email address, or website – then SMS will work perfectly for such. Carrying on conversations is awkward, and messaging services will work better for that.
Signal, Telegram, and WhatsApp are all messaging platforms. Most of these systems uses your mobile number as an identity, but others will use a username. Messaging platforms are better for carrying on a real-time conversation. With that being said, this is ideal for messages that are intended to be longer than SMS’s 140 character limit.
These platforms are intended for multiple paragraph communications. This is much longer than messaging clients, and may have a delay in replies. If you won’t spend a stamp on what you are writing, then email is probably not the best platform.
I have had people that would write an email comprising of one or two sentences, and then expects me to entertain them with a response. If you want to carry on a conversation with just one or two sentences at a time – consider using messaging clients, and platforms. Email is not intended for short communications.
On a personal note, I will likely not reply to someone that would only write one or two sentences. If I am in a good mood I might respond instructing them to write more than one or two sentences if they wish to get a reply from me. If the person chooses to not write back, then they are probably not what I would look for in email communications.