Validity (Everest) vs Warmy: Enterprise Email Deliverability Compared (2026)

Warmy’s email warmup works through the email provider you already have. The warming itself happens on a protected network of over a million real inboxes (Google Workspace, Microsoft 365, consumer accounts), and messages are timed to working hours in each recipient’s own time zone. It starts slow. Over the following weeks the volume grows, and it drops back at night and over weekends, which is roughly the pattern a person sending by hand would leave.

What happens on the other side matters just as much. Mailboxes in the network open what you send, reply to some of it, and mark a few messages important. If anything lands in spam, they move it back out. You pick the providers you want to warm with, and the templates and topics are yours to write too, in 30+ languages. Auto-archive files the warmup messages away so they never pile up in your inbox.

Warmy also gives you a 500,000+ US seed list covering Gmail, Outlook, Yahoo, corporate and regional providers, and that includes mobile seeds sitting on real US devices. You add the list to your normal campaign sends. The seed accounts then open your emails, drag them out of spam if they end up there, scroll through and click the links. So your real campaigns pick up engagement as well, on top of the peer-to-peer warmup traffic.

Start with authentication, because nothing else holds up without it. SPF, DKIM and DMARC are what Google’s sender requirements are built around. Open Warmy’s DMARC monitoring and you’ll see who’s sending mail as your domain, where the checks break, and which record you have to change. If you need new records, the free SPF and DMARC generators will build correct ones in a couple of minutes. Meanwhile, Warmy keeps watching your domain and IP reputation around the clock and pings you the moment a signal starts to slip.

Warmy runs its placement tests outside the warmup network, which keeps the numbers honest, and splits the results by provider into inbox, Promotions and spam. Scheduled auto-tests mean you’ve always got a fresh baseline. One thing we tell customers a lot: don’t change the template or the provider mix between tests, or you can’t really compare them. If Microsoft 365 makes up a big chunk of your list, pull those numbers out separately before you raise volume. A healthy overall score can hide a Microsoft problem.

These two solve different problems. Validity Sender Certification is an allowlist program. Senders who meet Validity’s requirements and pass its review get preferential treatment from mailbox providers, and they have to keep meeting those requirements to stay certified. It’s sold separately from Engage.

Warm-up is another thing entirely. It builds the sending history and engagement that mailbox providers look at for everyone, certified or not. Warmy starts warming new and existing mailboxes and domains on day one, whether or not Certification is in the picture. Run it before you apply, run it alongside, or skip Certification altogether.

Validity handles email rendering tests and pre-send QA through Litmus. Warmy doesn’t have a rendering suite. Instead, there’s a free Mobile Email Preview tool for checking how an email will look on a phone, plus the Templates AI optimizer, which gives your campaign an inbox score before you hit send.