Our domains had 3 SPF records for 8 months and it was quietly costing us

Not a huge story but it's a mistake I see constantly so figured I'd write it up.

We had a domain sending 150ish emails a day. Reply rates were fine at first then slowly ground down over a few months. Not a cliff just a slow bleed. 4% down to under 1%. Assumed it was list quality, changed offers, changed copy, changed sequences. None of it moved the needle.

Eventually ran the domain through a DNS checker instead of trial and erroring the copy for the 100th time. Found 3 separate SPF records. One was from the original Google Workspace setup, one got added when we hooked up a sending tool and a third got added months later when we tried a different one and never cleaned up the first two.

You can only have one SPF record per domain. Full sto!p!! When there's more than one most receiving servers either fail the check outright or just pick whichever one they feel like trusting, which is somehow worse because now it's inconsistent instead of predictably broken.

Fixed it in about 15 minutes. Reply rates weren't instant overnight but climbed back over the next couple weeks as reputation recovered.

While I was in there I also checked DKIM and DMARC since apparently I'd been ignoring all three for months!

DKIM key was still valid, but DMARC was sitting at p=hone which sounds like working setting but actually means "monitor but do nothing." Fine when you're first setting up, not fine 2 years later with zero enforcement and zero reporting

None of this throws an error anywhere. No warning email, no dashboard alert. It just slowly tanks your sender reputation while you're busy blaming your subject lines.

If your reply rates have been drifting down for no obvious reason and you haven't checked these in a while, it takes 10 minutes with any free DNS lookup tool. Cheap insurance against a problem that doesn't announce itself.