If you are on or aspiring to be on the tenure track, you will want to figure out whether the presses you’re thinking of approaching are considered reputable publishers in your field. Look to see if the press has recently published any well-known or senior scholars. Check to see if any of the press’s books have been reviewed in the major journals. And, if the very idea of it doesn’t make you want to run screaming, ask published colleagues their thoughts. They might be able to share information on or even an introduction to individual editors. One key thing to keep in mind is that some commercial presses that publish academic books may not perform peer review at all or to the standard expected by university tenure and promotion committees. Check with your department to be sure, as policies vary by university and by field.
That said, sadly, having a book contract does not guarantee you will get a tenure-track job or tenure, though in most cases securing one will demonstrate to hiring and tenure and promotion committees that your work has been formally recognized as having merit in your chosen field. Be very careful how you describe your relationship with your publisher on your vita. Having a proposal in review at a press is not the same as having a book manuscript in review, and having a book manuscript in review is not the same as having a contract for that project. Only if you have signed a formal publishing agreement is it accurate to list your manuscript as being “under contract.” Some hiring and tenure and promotion committees may even ask to see your book contract.