BIMI/DMARC Deliverability Wins
Email deliverability has become increasingly complex as inbox providers tighten their standards for sender authentication and engagement. This article breaks down five proven strategies that leading email marketers are using to improve their BIMI and DMARC implementation while maintaining healthy sender reputations. Experts in the field share practical tactics for list management, authentication alignment, and engagement-based segmentation that deliver measurable results.
Enforce Strict Alignment and Trim Inactive Contacts
The biggest shift I've seen for inbox placement at scale was moving DMARC from relaxed, "report-only" mode to strict alignment and enforcement.
Most senders sit on a DMARC record like:
v=DMARC1; p=none; rua=mailto:dmarc@domain.com
In practice that just collects reports. What helped was changing it to:
v=DMARC1; p=quarantine; rua=mailto:dmarc@domain.com; aspf=s; adkim=s
aspf=s and adkim=s mean SPF and DKIM must match the exact From domain. That closed the gap where some email came from a slightly different sending domain or subdomain. Once we fixed those, Gmail and Yahoo treated the traffic as more trustworthy, which showed up as better inboxing over a few weeks. After the reports were clean, moving p from quarantine to reject gave another small improvement because it stopped spoofed and misconfigured sends outright.
On the engagement side, the one suppression rule that moved opens most was cutting off dead contacts: no more campaigns to anyone with zero opens or clicks in the last 90 days, then moving them to a separate "win-back" stream with fewer sends. That trimmed volume, lowered spam complaints, and raised average engagement on the main list, which loops back into inbox placement for Gmail/Yahoo.
So, strict DMARC alignment with:
v=DMARC1; p=quarantine; rua=mailto:dmarc@domain.com; aspf=s; adkim=s
plus a 90-day inactivity suppression rule has been the clearest combo for better inboxing and higher open rates.
If you need my details:
Josiah Roche
Fractional CMO, Silver Atlas
www.silveratlas.org
Adopt 14-Day Sunset for New Leads
We treat new leads from paid ads as a liability until they prove otherwise. Most marketers wait 90 or 120 days to scrub inactive subscribers, but holding onto cold traffic that long creates a drag that destroys domain reputation with Gmail and Yahoo.
We implemented a strict 14-day sunset rule for new acquisitions. If a lead from Facebook or TikTok doesn't open an email within their first two weeks, they are immediately suppressed from our core mailing infrastructure. This aggressive culling maintains high engagement ratios, signaling to ISPs that our content is widely desired. That signal allows us to scale volume without triggering spam filters.
Jump Fast to Reject After Validation
The single change that had the biggest impact on inbox placement was implementing proper DMARC alignment with a p=reject policy - but the secret was in the timing, not just the policy itself.
Most advice says start with p=none for monitoring, move to p=quarantine, then eventually p=reject. That's safe but slow. What actually moved the needle was this: I set up DMARC at p=none with aggregate reporting, spent two weeks confirming all legitimate sends were aligned (SPF and DKIM both passing), then jumped straight to p=reject.
The DNS record looked like this:
v=DMARC1; p=reject; rua=mailto:dmarc@yourdomain.com; rfo=1; pct=100
Open rates jumped about 12-15% within a week. Gmail and Yahoo particularly rewarded it - emails that were previously landing in promotions started hitting primary inbox.
Why it worked: Mailbox providers see p=reject as a strong signal that you're serious about preventing spoofing. It tells them you've cleaned up your authentication and you're confident in your sending infrastructure. p=none or p=quarantine doesn't carry the same weight because half the internet has those set and never follows through.
The risk everyone worries about - legitimate email getting blocked - didn't materialize because we did the validation work upfront. The two-week monitoring period with p=none caught the one newsletter service that wasn't properly authenticated. Fixed that, then flipped to p=reject.
One caveat: This only works if your SPF and DKIM are already solid. If you're still figuring out authentication, don't skip the gradual approach. But if you know your infrastructure is clean, p=reject is the move that signals trust to mailbox providers.
Cut Off Three-Month Unopened Recipients
We stopped sending to anyone who hadn't opened in 90 days. That single suppression rule did more for our inbox placement than any DNS tweak.
Our emails go to founders raising capital, so engagement windows are tight. Someone who hasn't opened in 3 months probably isn't fundraising anymore. Keeping them on the list was hurting our sender reputation for no reason.
On the DNS side, moving DMARC from p=none to p=quarantine helped. But honestly the 90-day cutoff moved open rates more. We went from 25% to around 38% within two months.
Sending to fewer people got us better results. Smaller list, better placement, higher engagement.
Prioritize Hygiene and Add One-Click Unsubscribe
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DMARC got us compliant. Didn't move open rates. The suppression rule did.
We shipped SPF, DKIM, DMARC p=quarantine before February 2024. Inbox placement? Flat. The list was the culprit—40% hadn't opened anything in 90 days. Gmail saw us mailing corpses. Treated us accordingly.
Fix hurt. Anyone with zero opens in 90 days hit suppression. No exceptions. We axed 38% of our list overnight. Open rates climbed from 18% to 23% in six weeks. Complaints cratered to 0.08%.
DNS tweak that bit: one-click unsubscribe. Adding List-Unsubscribe-Post: List-Unsubscribe=One-Click slashed complaints in half. Postmaster confirmed it within days.
Cadence shift: 4/week dropped to 2 for anyone silent past 30 days. Frequency tied to behavior. Not the calendar.
Bottom line: authentication is table stakes. The war is list hygiene. Stop mailing the dead. They're not neutral—they're poison. Every ghost drags your engaged subscribers closer to spam.
