How to check the deliverability of my outgoing email (spam, dkim, dmarc, spf)

i know i'm gonna sound a lot dumb but I really tried to research this for a frew weeks and I can't find usefull information or clear one. Basically the project i'm working on is a newsletter builder, and i'm on its final steps. Now I need to verify spf dkim and dmark (which I don't know what they mean or how they work, so some clarifiance would be great). Then I also need to check if my email is considered as spam or if any of the news contain spam (separately). I tried to read documentation of 2 great spamcheckers (spamassassin and rspamd) and I couldn't understand anything about how they are supposed to be integrated on my project. I think all my problems are due to my lack of knowledge related to emails / email servers and stuff related. I'd really appreciate if someone could enlight me about what are the steps that I need to do, if I really need to setup an email server to test this out and how to do it etc etc... I'm really in the dark here. I know the enterprise i'm doing this work for already was sending emails from their domain but I don't think they gave me access to that.

Thanks for all your attention, merry christmas to you all

Best regards