If the message is long enough to actually have multiple sentences, each individual sentence has a period. The last sentence simply drops the period. It's not t

If the message is long enough to actually have multiple sentences, each individual sentence has a period. The last sentence simply drops the period. It's not the use of periods on a per-sentence basis, it's just the last period. For certain demographics this evokes a tone of abrupt and unfriendly finality. But it depends on context.