The only place you’ll see any savings with your short messages is in storage. Assume you use gmail to send stuff to other gmail users. Google stores all the messages you send and all the messages the others receive. Google is building new data centers all the time and these use lots of energy.
Maybe not as much as you might think. Most hard drive storage is allocated in blocks, not bytes, and reducing the true size of a file may not reduce the number of blocks needed.
For example, if the block size is 64KB, any file from one byte to 64K will take up one block. A 65KB file would take up two, or 128KB.
Block size allocations have tended to get larger over time, since the average file size is getting bigger, and there typically is a speed advantage to reading a small number of large blocks compared to a large number of small ones.
Sure, some systems can be optimized for smaller files, but with the cost of storage declining, it’s usually not worth the effort.