What is the “Reply-To” header?
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The Reply-To header tells your recipient's mail client where to send their reply. By default, replies go back to whatever address is in the From field. But when you add a Reply-To header, you're saying "Actually, send replies to this address instead."
Think of it like this: the From address is who the email appears to be from. The Reply-To address is where you actually want the conversation to happen. They're often the same, but sometimes you need them to be different.
When you'd use Reply-To differently from From:
- No-reply addresses that still collect replies: You send from newsletter@brand.com but want replies to land in support@brand.com. The reader hits reply, and their message goes where your team will actually see it.
- Personal brand with a team inbox: You send newsletters from jane@brand.com so your name shows up, but replies go to hello@brand.com where your whole team can respond.
- Department addresses: Marketing sends from marketing@company.com but wants replies handled by customer-service@company.com.
- Forwarded newsletters: Some readers forward your newsletter to friends. If you set Reply-To to your support address, those friends can reply directly to you instead of bothering the person who forwarded it.
Most ESPs (Mailchimp, Brevo, Klaviyo) let you configure Reply-To in your campaign settings. Look for "Reply-To address" or "Reply address" in the sender options. If you're sending through SMTP directly, you add it as a standard email header just like From and Subject.
A common mistake: setting Reply-To to a real address but forgetting to monitor that inbox. If you tell people to reply somewhere, someone has to actually check it. Another mistake: using Reply-To to hide a sketchy From address. That's a spam signal. The From and Reply-To should both be addresses you control and that make sense for your brand.
One more thing: if you're using a no-reply address (like noreply@brand.com), setting a Reply-To won't magically make it OK. Readers hate no-reply addresses because they signal "we don't want to hear from you." If you're going to use one, at least set Reply-To to somewhere your team monitors. Better yet, use a real monitored address in the From field to begin with. Want to see what Reply-To your emails are actually using? Forward one to yourself, view the full headers, and look for "Reply-To:" in the header block. Not there? Then replies go back to the From address by default.
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