Every direct mail article on the internet quotes a response rate comparison, and half of them round the numbers until they squeak. Let me give you the honest version, sources included, plus the part most articles skip: response rate alone should not pick your channel.
The benchmark numbers
The ANA's response rate research (which absorbed the DMA's long-running report series) has for years shown direct mail response in the single-digit percentage range, with house lists, meaning existing customers, meaningfully outperforming cold prospect lists. Compilations of the recent reports, like Postalytics' statistics roundup, place typical letter-size mail response around the 4% mark against email response commonly measured in fractions of a percent.
Directionally, mail's response advantage over email is not close, and it has persisted across every report cycle I have read. The mailbox is simply less crowded than the inbox, and the piece physically sits in the home. JICMAIL's panel measures direct mail items being interacted with about 4.5 times and living in the home for over a week.
The comparison that actually matters
Response rate is a numerator without a denominator. Email is nearly free to send; mail costs real money per piece. The honest comparison is cost per response and, one level deeper, cost per acquired customer.
Run the arithmetic on your own numbers. A 4% response on a postcard costing about 80 cents all-in is roughly $20 per response. An 0.1% response on email that costs a tenth of a cent to send is about $1 per response. Email wins that race every time it can reach the person at all, and that is the catch: email only works on people whose addresses you have and whose attention you have not already burned. Mail reaches every household on a street, including the ones no marketer has an opt-in for.
How I actually use the two channels
Email is for people who already know you. Mail is for reach, for high-value offers where $19 per response is a bargain, and for re-engaging people who stopped opening. The channels also compound: industry integration studies consistently report double-digit response lifts when mail and digital run together, which I dug into in my omnichannel piece.
One closing caveat: none of these benchmarks matter if you cannot measure your own response. An untracked campaign makes you argue from industry averages forever. A tracked one gives you your own response rate by neighborhood after a single drop, and that number beats every benchmark on this page.