Well, this is a source of consternation! Some of the best literary journals where I hope to someday share my poetry will not accept anything that has been posted anywhere on the internet. So, beware my scribbling friends. Unless you choose to primarily share your poetry with the world by means of your blog or through some other internet means, be very careful what you post. The literary journal "Poetry" is one such journal. Of course, this standard doesn't apply to all literary journals. There are still many that will accept work that has been on the internet.
There is also a lot to be said for just tossing all of those journals out the window; there could be a sense of satisfaction in rejecting them for a change - give them a taste of their own medicine. Sharing our writing by means of a blog or through any of those other on-line sources could be quite satisfying. Lord knows there isn't any money to be made in poetry anyway. And, most of us have to die before we acquire any real notoriety. If "Poetry" hasn't accepted any of my precious pennings by the time I'm, say, 90 years old, I'll gladly post them on my blog if I still remember where it is and my arthritic fingers can still type.