"health check" for emails inboxing

Is there anyway to hack or get a health check to get a general sense of if our emails are getting to the inbox vs the spam/junk folder?

Our open rates are going down but not drastically, and we recently started using a new domain, so I am starting to think we are going into junk.

But I don't think it warrants purchasing a full solution to continually monitor...not just yet anyway.

Any input is appreciated!