Last week, my newsletter almost died.
Ok, I’m being a bit dramatic but that’s what it felt like when my open rates had tanked to 16%, my emails were sent straight to spam, and Outlook was showing an “unverified sender” ….warning telling recipients not to trust me.
If you’re reading this because your Beehiiv custom domain is triggering unverified sender Outlook errors, I’ve been exactly where you are.
The problem started after changing my domain
Initially, I registered my newsletter with a subdomain (say, news(dot)mysite(dot)com). Everything worked fine. Then I decided to move to my root domain (mysite(dot)com) for branding reasons. I upgraded to a Namecheap webhosting account, updated my CNAME records, pointed everything to a landing page, and assumed I was good to go.
That’s when the unverified sender Outlook warnings started appearing.
My TXT records hadn’t changed. My SPF, DKIM, and DMARC all showed as authenticated. On paper, everything looked perfect. But my emails started getting massacred by spam filters. Microsoft Outlook slapped a bright red “unverified sender” warning on my messages. My delivery rate dropped to 90%.
Ran my domain through Spamhaus and the infrastructure score sat at a painful -2.
It was quite weird. I was on the same domain, built my list through ads and social media (all opted in, following best practices), but suddenly people weren’t even seeing my emails. The change was killing my newsletter.
What causes the unverified sender Outlook warning?
Here’s what nobody tells you about switching your Beehiiv custom domain: changing DNS records can trigger a complete rescan of your domain by email providers. Even if your authentication passes, the sudden pattern change looks suspicious to Outlook and other providers.
Two experienced email marketers helped me understand what was really happening behind the scenes:
The configuration mismatch. When you move from a subdomain to root domain, your ESP might still be configured for the old setup even though your DNS looks correct. This creates the unverified sender Outlook warning that won’t go away until you fix the underlying Beehiiv custom domain configuration.
The infrastructure score problem. A -2 Spamhaus infrastructure score is serious. It usually means a few things: could be that your domain has very low historical engagement or the shared IP you’re sending from has been burned by other users. This score alone can trigger unverified sender Outlook warnings regardless of authentication.
The reputation problem. Perfect DNS records mean nothing if your sender reputation is damaged. When Outlook puts an unverified sender warning on your emails, it means they’ve lost trust in your traffic pattern. Your domain or sending IP has been flagged based on engagement signals, not technical configurations.
My Beehiiv custom domain configuration was broken
After digging deeper, I discovered the actual problem causing the unverified sender Outlook warning. My Beehiiv custom domain settings were still configured for my old subdomain (news(dot)mysite(dot)com) even though I had changed everything on the DNS side. The platform showed my domain as “verified,” so I assumed everything was working. It wasn’t.
This mismatch between what Beehiiv was sending from and what my DNS authorized was triggering the unverified sender warnings from Outlook. My emails were technically authenticated, but the configuration inconsistency made everything look suspicious to receiving servers.
How I fixed it
Here’s exactly what I did to fix it:
Step 1: Check Your Beehiiv Custom Domain Configuration
Go to Settings → Domains in your Beehiiv dashboard. I discovered my email domain was verified but my branded domain wasn’t verified. I then checked my Namecheap Zone editor and didn’t see my Beehiiv DNS details in there either. This was the smoking gun.
Step 2: Reverify Your Beehiiv Custom Domain
I first tried using Beehiiv’s automatic verification service (Entri – which lets you confirm domain ownership by logging into your domain registrar directly through Beehiiv). For me this didn’t work.
Step 3: Manually added DNS records
I copied all the DNS records from Beehiiv and manually pasted them into my Namecheap Zone editor. Since the automatic verification methods weren’t working (was this why things broke in the first place -who knows?)
Important note: if you’ve moved to a webhosting plan with Namecheap, you can only change DNS records in the Zone editor, not in your account panel.
This manual update finally synced everything correctly. Beehiiv’s mail servers were no longer trying to send from my old subdomain configuration, which removed the warning.
Step 4: Fix Your Email Content to Avoid Future Deliverability Issues
While fixing the technical issues with my Beehiiv custom domain, I also cleaned up my email content. I had been sending 1500+ word emails packed with multiple links. Bad idea. Long emails with heavy link density scream “marketing spam” to filters, especially on newer domains, and can contribute to unverified sender warnings.
I cut my emails down to under 500 words and limited links to 2 or 3 maximum.
Post-fix results
I sent an email the day after fixing my Beehiiv custom domain configuration. The difference was dramatic:
- The Outlook warning disappeared completely.
- Delivery rate jumped from 90% to 98.49%. Nearly every email reached an inbox.
- Open rates doubled from 16% to 32%. People were actually seeing my emails again.
The Spamhaus infrastructure score still showed -2, but I’m not worried. The reputation scores might be taking time to update. As long as I maintain good engagement and follow email best practices, the score will recover.
Key lessons
If you’re struggling with unverified sender Outlook warnings after setting up your Beehiiv custom domain, here’s what matters:
Double-check that your Beehiiv custom domain settings match those with your DNS provider. Just because Beehiiv shows your sending domain as “verified” doesn’t mean the configuration actually works correctly. Go into your domain records and check, especially if you’ve made recent DNS changes
DNS changes trigger rescans and unverified sender warnings. Moving from a subdomain to root domain (or vice versa) can make email providers like Outlook suspicious even if your authentication is perfect. Be prepared for your emails to temporarily end up in the junk folder
Content matters as much as Beehiiv custom domain configuration. Even with perfect DNS records, long emails with tons of links will hurt you and potentially trigger unverified sender Outlook warnings. Keep messages short and link density low.
Reputation is behavioral, not technical. You can’t DNS your way out of poor engagement. Regularly send mail to engaged subscribers, keep volume low while rebuilding trust, and prioritize quality over quantity.
Moving forward
I’m now following strict email best practices. Shorter emails, minimal links, and focusing only on engaged subscribers. My newsletter is back on track, and I’ve seen an improvement in my metrics already
The technical setup of your Beehiiv custom domain matters, but your sender reputation matters more. Fix your configuration first, then earn back trust through consistent, valuable content that people actually want to read. That’s how you permanently solve your deliverability and trust problems.