Are there limits on the number of TXT records per domain?
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If you're setting up SPF, DKIM, and DMARC and wondering whether you're about to hit some kind of TXT record ceiling, the short answer is: probably not. But there are a few real-world limits worth knowing.
The DNS protocol itself doesn't cap the number of TXT records on a domain. You can technically have as many as you need. What actually matters is where those records live and what they're for.
Where limits do exist
Some DNS hosting providers impose their own caps on total records or records per hostname. These vary widely, so it's worth checking your specific provider's documentation if you're managing a large setup with many DKIM selectors across multiple ESPs.
Still the other real limit is practical: DNS responses travel over UDP, which has a packet size ceiling of around 512 bytes. If your DNS zone gets large enough that responses need to exceed that, the query falls back to TCP. This is rarely a problem for email authentication alone, but it's worth knowing the mechanism.
What plays nicely together vs. what doesn't
Different authentication records coexist fine at different hostnames. Your SPF record lives at your root domain, DMARC lives at _dmarc.yourdomain.com, and each DKIM selector lives at its own subdomain like selector1._domainkey.yourdomain.com. These don't conflict.
What does break things is having two records of the same type at the same hostname. Two SPF records at your root domain causes a permerror and your SPF check fails entirely. Two DMARC records at _dmarc causes the same problem. Same protocol, same name, that's a conflict every time.
A typical setup running SPF, DMARC, and a handful of DKIM selectors (say, one for your main ESP plus a couple for other tools) sits comfortably in a range that causes zero issues. You'd need an unusually large number of integrations to approach any realistic limit.
Not sure if your current TXT records are set up cleanly? You can check your SPF with our free SPF checker or your DKIM with our DKIM record lookup, both take about 30 seconds.
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