Improving your deliverability

Mailbox providers like Gmail, Yahoo and Outlook decide where each email lands, and they don’t publish their rules. What they reward is mail that looks wanted: sent to people who asked for it, opened and clicked, rarely reported as spam. The recommendations below make your newsletters look like that. They can’t guarantee inbox placement, but they’re what gives you the best chance.

Some of this Letterhead already does for you, such as cleaning bounced addresses and honoring unsubscribes. See Knowing what Letterhead handles for you.

What helps

• Send only to people who asked. Every reader should have deliberately subscribed. Double opt-in, where a reader confirms their address, is the strongest proof.
• Keep your list clean. Stop sending to readers who never open or click. List cleanup can do this for you, and engagement-based segments let you mail your active readers.
• Send on a steady schedule. Sudden jumps in volume look suspicious. If you’re moving from another platform or growing fast, ramp up gradually; see Warming up your sending reputation.
• Authenticate your domain. Set up DKIM, SPF and DMARC on your sending domain. If you send from Letterhead’s own domain, this is already done; for your own domain, see setting up your sending domain.
• Be clear about who you are. Use a recognizable From name, a real Reply-to address and an honest subject line.
• Ask readers to add you to their contacts. It tells their mailbox your email is wanted.
• Check before you send. The Content Check panel flags broken links and content providers tend to refuse.

What to avoid

• Buying lists, or sending to addresses you didn’t collect yourself.
• Selling or sharing your list without permission.
• Hiding the unsubscribe link or ignoring unsubscribe requests.
• Deceptive subject lines or a disguised sender.
• Subject lines in all caps, with excessive punctuation (”!!!”) or phrases like “URGENT” or “FREE MONEY”.
• Sending without testing and proofreading.

Why an email might land in spam

When a newsletter starts landing in spam, the cause is usually one of these:

• Engagement dropped. Providers notice when readers ignore, delete or report your email, and start filtering it.
• Your reputation slipped. Sending to old or invalid addresses, hitting spam traps (abandoned addresses providers use to catch careless senders), or a rise in complaints all count against you, and complaints can land a domain or IP on a blocklist.
• Your sending changed. A sudden change in volume or schedule can look like a different sender.
• The content triggered a filter. Even with a clean list and a good reputation, spammy-looking content can be filtered.

Providers update their filters constantly, so a newsletter that did well last month can struggle this month without anything on your side changing. To see how your mail is landing, check your List Health page, and if you send to many Gmail readers, connect Google Postmaster.

When to contact us

If you’re following these practices and a mailbox provider is still refusing or filtering your mail, contact [email protected] and we’ll look into it. For industry-standard guidance, see the M3AAWG Sender Best Common Practices.