Hi! We send maybe 5 emails a day through AWS SES from a dedicated subdomain. SPF, DKIM, DMARC p=none, custom MAIL FROM, all set up correctly, auth passes at the first hop.
I test send to a recipient on Mimecast into Microsoft 365 and it landed in Junk. Mimecast modified the mail during inspection and the broke DKIM body hash. By the time it hit M365 everything failed (SPF, DKIM, DMARC), ARC pass but not trusted, which got it classified as spam.
At this volume I can't build reputation. Postmaster Tools and SNDS won't even show data. Been told to switch to Postmark or Resend for shared-pool reputation but skeptical it helps at <100/month. Anyone actually getting consistent inbox at Mimecast/Proofpoint shops as a tiny sender, or is this just life? Does p=quarantine move the needle on placement? Is Postmark/Resend sensible at this volume?
Im open for any tips you got.