The Email Deliverability Checklist Before You Start Cold Outreach

Most deliverability problems in cold outreach aren't caused by warmup — they're caused by DNS misconfiguration that was there from day one. Before you spend weeks warming up a mailbox, it's worth ten minutes checking the three records that determine whether receiving servers trust your domain at all.

SPF: who's allowed to send as you

SPF (Sender Policy Framework) is a DNS TXT record that lists which mail servers are authorized to send email on behalf of your domain. A record like v=spf1 include:_spf.google.com ~all tells receiving servers "only these listed servers should be sending mail claiming to be from this domain." Without a valid SPF record, or with one that doesn't include the server you're actually sending from, receiving filters have a much easier justification for treating your email as suspicious — it genuinely looks like someone else forging your domain.

DKIM: proving the message wasn't tampered with

DKIM (DomainKeys Identified Mail) attaches a cryptographic signature to outgoing email, generated with a private key and verified against a public key published in your DNS as a TXT record under a selector-specific subdomain (something like google._domainkey.yourdomain.com). If the signature verifies, the receiving server knows the message wasn't altered in transit and really did originate from a server holding your private key.

The tricky part with DKIM is that the selector — the specific subdomain prefix — varies by provider and by configuration, and there's no universal way to look it up if you don't already know it. Google Workspace commonly uses a selector literally named google; Microsoft 365 setups commonly use selector1 or selector2. If you've set up custom DKIM through a different email service, your selector might be something else entirely, and checking tools that only try one or two common selectors will report "not configured" even when DKIM is actually set up correctly under a different selector name.

MX: where mail bound for your domain goes

MX (Mail Exchange) records tell the internet which servers handle incoming mail for your domain. This one is more about receiving than sending, but a missing or misconfigured MX record is a strong signal to filters that a domain isn't a legitimately operated mail domain — it's the kind of thing a domain registered purely to send spam would neglect to set up properly.

Checking these three records yourself

You can check all three manually with dig or any DNS lookup tool:

dig TXT yourdomain.com
dig TXT selector1._domainkey.yourdomain.com
dig MX yourdomain.com

The first checks for a v=spf1 record, the second checks DKIM under a commonly-used selector name for your provider, and the third confirms mail servers are configured to receive mail for your domain.

This works, but it's tedious to repeat every time you connect a new mailbox or troubleshoot a deliverability drop, and you have to already know which DKIM selector to check.

Testing where your email actually lands

DNS records being correctly configured doesn't guarantee your email lands in the inbox — it's a necessary condition, not a sufficient one. The only way to know for certain where a specific email actually lands is to send a real test message to real mailboxes and check the result: inbox, spam, or missing entirely.

This is exactly the gap a good spam placement test closes: send a probe email to a handful of independent mailboxes, wait for delivery, then check which folder it landed in on each one. It won't catch every possible filtering scenario a real recipient's provider might apply, but it catches the two most common failure modes — broken authentication and being pre-emptively junked by an aggressive spam filter — in minutes rather than after a failed campaign.

If you're setting up outreach on Microsoft 365 specifically, WarmRamp's free Checks tool runs the SPF/DKIM/MX lookups above automatically (including trying the common M365 DKIM selectors), and the Spam Checker sends a real one-off test to a handful of mailboxes and reports back where it landed — both before you commit a single mailbox to a multi-week warmup cycle.