GlockApps can help you "check if your emails are spam free and deliverable." I am told that they provide seedlist-based inbox monitoring, email spam checker and DMARC analytics.
Inboxable by Yesmail offers detailed inboxing, spam placement and blocking rate reporting, deliverability metrics by geographic region/ISP, and "Inbox Sub-Folder Placement" -- this last feature "showcases which inbox folder a message landed in at ISPs that now have sub-folders within the Inbox." (Gmail tab placement, I take it?)
Mail Monitor provides inbox placement tracking, spam filter analysis, duration testing (how long, after hitting send, did it take for the message to deliver?), reputation tracking, and more.
My apologies for the brief descriptions, as I'm not very familiar with any of these.
And do you remember Pivotal Veracity? Acquired by Unica, then Unica was acquired by IBM, and now that business has been spun out to Acoustic.