Why Your Emails Land in Spam and How to Fix It

"I never got your email. Oh wait, it was in my spam folder." Few phrases are more frustrating for a small business, church or nonprofit, especially when the message was an invoice, a registration confirmation or a newsletter people signed up for.

Spam filters weigh many signals, and there is rarely a single magic fix. But the common causes are well known. Work through this checklist in order, starting with the most important.

How spam filters decide

Mailbox providers look at several kinds of evidence:

• Authentication: can the message prove it came from someone allowed to send for your domain?
• Reputation: what is the history of your domain and the servers sending your mail?
• Recipient behavior: do people open, reply to and keep your messages, or delete them and mark them as spam?
• Content and links: does the message look like known spam or phishing?
• Technical setup: are servers and messages configured correctly?

1. Check authentication first

If SPF, DKIM and DMARC are missing or misconfigured, many providers treat your mail with suspicion. Make sure every service that sends as your domain, including newsletter tools, invoicing software and website forms, is authenticated. Our guide to SPF, DKIM and DMARC walks through it.

2. Send from your own domain

Messages that claim to come from a free email address but are sent through a newsletter or business tool often fail authentication checks. Use an address on your organization's own domain. See why your business email should use your own domain.

3. Clean up your list

List quality is one of the biggest factors for newsletters and announcements.

• Send only to people who asked to hear from you. Never buy or rent email lists.
• Remove addresses that bounce. Repeated sends to invalid addresses damage your reputation.
• Re-confirm or remove long-inactive subscribers. Very old addresses can be abandoned or even converted into traps that identify careless senders.
• Use confirmed opt-in where practical, sending a confirmation email before adding someone to your list.

4. Make unsubscribing easy

People who cannot find an unsubscribe link often click "Report spam" instead, which hurts your reputation far more than an unsubscribe. Include a clear unsubscribe link in every marketing message, support one-click unsubscribe where your email platform offers it, and honor requests promptly. Major mailbox providers expect this from bulk senders.

5. Review your content

Content alone rarely causes spam filtering, but it can tip the balance:

• Avoid misleading subject lines, excessive capital letters and lots of exclamation points.
• Make sure link text matches where links actually go, and avoid link shorteners.
• Do not send emails that are a single large image with little text.
• Be cautious with attachments in bulk email; link to files instead.
• Keep your sender name consistent and recognizable.

6. Watch your sending patterns

• Avoid sudden large spikes. If you normally email a few dozen people and suddenly send to thousands, providers notice.
• Warm up new domains and services by starting with smaller sends to your most engaged recipients and increasing gradually.
• Send consistently rather than in rare bursts.

7. Fix website form email

Many small websites send contact form notifications directly from the web server, using your domain without authentication. Those messages often land in spam or disappear. Configure your website to send through your email provider or a dedicated sending service, properly authenticated.

8. Separate transactional and marketing mail

Receipts, password resets and confirmations are important and expected. Newsletters are optional. When possible, send them through separate streams or services, so a marketing reputation problem does not delay a customer's receipt.

How to investigate

• Send test messages to accounts you control at several major providers and see where they land.
• Look at the message headers of a delivered test. They include authentication results showing whether SPF, DKIM and DMARC passed.
• Use provider tools. Google Postmaster Tools, for example, shows reputation and spam rate data for domains that send substantial volumes to Gmail.
• Ask recipients to add you to their contacts and to move your message out of spam, which helps future delivery for them.

If your domain or server is on a blocklist

Public blocklists track sources of spam, and mailbox providers may consult them. If you send through a reputable email service, its team usually manages server reputation for you. If you run your own mail server, check whether its address appears on common blocklists, fix the cause, such as a compromised account or open relay, and then follow each list's removal process. Removal without fixing the cause rarely lasts.

Keep it healthy

Deliverability is earned over time by sending wanted, well-authenticated mail to people who asked for it. Review bounces and complaints after every campaign, keep your list clean, and recheck authentication whenever you add a new tool that sends email on your behalf.