In the course of my research I have found that many publishers, especially the very large ones, do not take “unsolicited” manuscripts.
I presume by this they mean one must have an agent.
Yet there are also some publishers who will take manuscripts direct from a writer. In the case of the latter does the publisher also act as the agent ie: marketing the book, looking for ways to attract attention, looking for new markets for the book, acting as deal broker between author and publishing overseas/translations etc? In other words, how much does an agent differ from a publisher who takes manuscripts and publishes directly?
Small publishers are often willing to take on the expense of publishing and printing books in which they have faith, but they have to rely on the authors themselves to publicise its existence. The book will be properly registered with copies for posterity in six National Library Archives and it will be available on Amazon and can be ordered from all bookshops. Authors can buy any quantity of their own books at a substantial discount, at any time, but they are not obliged to do so …it is not vanity publishing!!
There is nothing against any author employing an agent to market the books, if they think it worth while.