In the case where much or all of the submission is similar to a discussion-type journal article that has been rejected (which may be stated on the journal’s website as “publication is not foreseen”), the AMS Publications Commission recommends rejecting the manuscript before peer review.
The web pages of these journals may state that such papers are equivalent to conference preprints and thus could be submitted to and published in other journals, but the perception of formal publication indicates that the ability of readers to determine the definitive version of the manuscript is compromised by its presence on another journal's web page.