Delivered is not the same as seen
A message can be accepted by a recipient’s mail server and still never be read. It might sit in a junk folder, a promotions tab or a bulk mail area. Deliverability is the broad question of whether your email reaches the inbox, and the answer is never a guarantee. Mail providers make their own decisions, they do not publish exact rules, and their methods change. What follows are general practices that tend to help, not a formula.
Why filters exist
Most email in the world is unwanted. Mail providers run filters to protect users from junk, fraud and malicious messages, including phishing emails that imitate trusted organizations. Filters look at many signals at once, and a single factor rarely decides the outcome. The signals generally fall into a few groups.
Sender reputation. Providers keep track of how recipients react to mail from a given sender. Many complaints, many messages sent to invalid addresses and sudden bursts of volume can count against you. A steady history of wanted mail counts in your favor.
Reader behavior. If recipients open, reply to or move your messages out of junk, that tends to be a positive sign. If they delete without opening or mark messages as spam, that tends to be a negative one.
Technical setup. Providers check whether a message really comes from the domain it claims. This is where sender authentication comes in.
Content. Filters examine wording, links, images and formatting for patterns common in junk.
Sender authentication in plain terms
Authentication is a way for a domain owner to prove that a message was sent with their permission. Without getting too technical, it usually involves records set up in your domain’s settings that tell receiving servers which systems are allowed to send mail for you, and that attach a digital signature to your messages. Many mail providers expect these to be in place, especially for larger senders.
Most email sending tools give instructions for adding the needed records. If you are not comfortable editing domain settings, ask whoever manages your domain, or check your sending tool’s help pages. Doing this correctly matters because mistakes can cause legitimate mail to be rejected. A basic grasp of domain names helps you see where these settings live.
Practices that tend to help
Send only to people who asked. This is the strongest single habit. Buying lists or emailing people who never agreed is the quickest way to attract complaints. See building an email list the respectful way and the notes on email consent.
Make unsubscribing easy. A reader who can leave simply is less likely to hit the spam button.
Keep the list clean. Remove addresses that bounce repeatedly, and consider pruning readers who have not engaged for a long time. A smaller, active list often does better than a large, ignored one.
Be consistent. Send from the same recognizable name and address at a regular rhythm. Sudden jumps from silence to a large send can look suspicious.
Warm up gradually. If you are starting a new sending address or domain, begin with smaller sends to your most engaged readers and increase over time instead of mailing everyone at once.
Write honestly. Subject lines should describe the content. Deceptive or pressured wording can cause both filters and readers to react badly. See writing email subject lines that are clear and honest.
Keep messages tidy. Use a reasonable balance of text and images, avoid very large images, check that links lead where they say, and avoid unnecessary link shorteners. Be careful with attachments, which are often treated cautiously.
Include real contact details. A clear sender name and a way to reach you build trust with both readers and filters.
Things people often get wrong
A common belief is that certain words, such as “free,” will always send a message to junk. In reality, filters weigh many factors, and a single word seldom decides the outcome. Avoiding exaggerated language is wise for readers anyway, but worrying about a word list can distract from the larger factors: permission, reputation and engagement.
Another mistake is treating open rates as an exact measure of inbox placement. Open rates are affected by how mail apps handle images and privacy settings, so they are only a rough clue. Understanding open rates and click rates helps you read the numbers with appropriate caution.
Checking for problems
Warning signs include a sudden drop in opens or clicks, a rise in bounces, or readers telling you they find your messages in junk. If this happens:
- Send yourself and a few friendly contacts test messages and see where they land.
- Check that authentication records are still correct.
- Look at your list for stale or suspicious addresses.
- Review recent subject lines and content for anything that might look misleading.
- Check your sending tool’s reports for complaints and bounces.
You can also ask readers to add your address to their contacts or to move a message out of junk, which may help for their mailbox, though it does not fix a wider problem.
Keep the goal in perspective
Filters are not out to get legitimate senders. They respond to what recipients tend to want. If you build your list with permission, write messages people value and keep your records tidy, you are working with filters instead of against them. Even then, some messages will end up in junk folders, so it helps to keep other ways of reaching your audience, such as a page readers can visit.