Anyone who writes poetry and sends it out to editors, will in return receive rejections.
The poet needs to learn to accept this fact and use it to become a better poet.
There are times when a rejection does not reflect upon the quality of the work in any way. It may be simply not what the editor was looking for or needing at the time.
Quite often though it is an indication that the editor sees a poem that isn't yet quite what it could be, or he or she sees an attempt that has been sloppily composed, or sometimes it can be just a little mishap here and there that jars.
Sometimes the editor doesn't see a poem at all. Sometimes what has been submitted is something one would say in conversation to a friend, or to the lady sitting next to us on a bus. Poetry doesn't generally talk the way we do everyday because it is reaching out for something new: a newness in apprehension, a newness in expression. But that is not to say that a poem cannot ever be like a chat to the lady on the bus. That is the nature of poetry that it can be whatever it needs to be.
One of the problems a poet faces is that it is difficult for any of us to see our writing as it is. One obstacle is that our brains love short cuts. We tend to fill in what we know should be there. For instance, this is what makes proofreading difficult, we mentally fill in the missing words, mentally correct the spelling because we know it should be there.
Sometimes a poem virtually writes itself. But that is rare. On most occasions a poem will need lots of revision over time. Then the problem that arises is that we have become blind to the poem as it is because we read into it all that we have thought about during the process of writing it; which will not be present for the readers. So they might find it baffling.
We might show it to others before sending it out, to see how they read it. But not everyone likes and appreciates the same poems, so we need to consider carefully any advice received. We really should put the poem aside for a time and forget it. Then we can approach it again as if we are seeing it for the first time. We might be appalled, or we might be delighted with what we find there. Usually it is a true assessment of the state of the poem's being.