Spam Resource: All Things Deliverability

Besides Return Path and 250ok (now both owned by Validity ), and eDataSource (now owned by SparkPost ), here are three other deliverability monitoring vendors, as shared by kind commenters on my previous post : 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 an…