I'm talking about pictures of cats or flowers or a meme, nothing extreme. Is it technically legal or illegal for me to do this?
Generally speaking, it is illegal for you to do this.
Copyright gives the creator of the image the exclusive right to copy it, and just making copies to send to other people is probably not going to be fair use. Making copies without a license from the copyright holder would therefore be copyright infringement.
Are there likely to be any consequences for doing this? Probably not.