Judging from the comments yesterday, a few people are not clear about the issue of blogs and publishing.
Think of it - anyone in the whole world who has access to the internet can read your blog. If that's not publishing, what is? Of course it feels as if we are just chatting to our friends here.
But: the IRS have chased people up based on what is on their blog (so don't admit to receiving untaxed money)
People have been fired for what they put on their blog (so don't rant about your job, your boss, your co-workers, and don't give away confidential information)
The CIA has investigated people for things posted on their blog (so don't make bad jokes about terrorists).
And if you want to publish a poem, read the submission guidelines for the magazines you want to publish in. They will probably say "previously unpublished work". Yes, this means "not published anywhere, even on your blog".
You could just cross your fingers and hope they won't find out. They probably won't. Most editors don't have time to check out everything - although it would be very easy to enter a line or two of your poem in google. That would reveal it straight away.
Basically, they want to sell magazines. They don't want to think their potential readership will be put off buying their magazine, because they have already seen the content elsewhere. And the people who are interested in reading poetry in magazines are probably the same people interested in reading it online.
Then there is the matter of e-mail lists. Most of these archive previous posts. Often, you don't even have to be subscribed to the list to search the archives. This, too, is publishing. I personally will share poems on a list I belong to which has closed membership and doesn't archive work. It is also OK to send a poem in a private e-mail to a friend - this is the same as showing the poem to your friend in person, or sending it by snail mail.
Books are slightly different from magazines. Most books of poetry will give a list of magazines in which work previously appeared. In other words, it is not usually all unpublished work. so you can put a poem in a book if it's already been in a magazine, but you can't put it in a magazine if it's already been in a book (unless you are the editor and then you can do whatever you want to).
Those who have already put poems on their blog, and want to send them to magazines - personally, in that case I'd send them out anyway. If you get caught out, and you probably won't, plead innocence. But just to be on the safe side, I'm not sharing anything here unless I have either published it, or been rejected enough times that I've given up on publishing it, or decided that I'm not sending that particular poem out for publication.
I hope that's all clear now