Sorry to be blunt, but, if you USE ALL CAPS in your email or social media posts, you will immediately make yourself seem inexperienced or ignorant.
Most experienced computer users consider the use of all capital letters to be the Internet equivalent of shouting.
For those of us who spend a lot of time hanging out in cyberspace, messages written in all capital letters are reminiscent of trying to hold a conversation in which one person is shouting every word while others are speaking at a normal volume.
Also, a message written in all capitals is harder to read. In blocks of text rendered in all capitals, words lose their “shape” because they are all the same height. Each word becomes a uniform rectangle. Most people read and quickly recognize words by looking at their overall shape. We do not read by visualising words one letter at a time.
Capital letters are best left for their intended usage and, sparingly, to emphasize a particular word or phrase.
Perhaps this restriction on the use of capital letters might seem silly to you and you might dismiss it as unimportant. However, using all capitals in your messages will adversely affect how people perceive you online.