Why are notifications sent through the system always blocked automatically? Or marked as spam?

Many sites have the ability to send some kind of notification email to users, such as a password retrieval email for a WordPress system or a WooCommerce order notification. But these messages are often blocked or marked as spam by the receiving mail server. Why? How to solve this problem?

What is an anti-spam system

Most post office servers have an anti-spam system deployed. Any mail sent to the system that triggers the anti-spam rule is rejected or marked as spam. So to solve the problems mentioned above, you must first understand some basic rules of anti-spam.

Anti-spam system generally can be set to whitelist or blacklist, most of the public email address (such as QQ mailbox, netease mail, etc.) usually adopt the blacklist mode, will put some in a blacklist often send spam domains, such as server IP information added to intercept or mark spam list.

What is spam?

  1. Spam generally refers to unsolicited e-mails, which fall into the category of spam if they meet the following characteristics:
  2. Other messages sent to recipients from addresses that have been rejected;
  3. Messages from blacklisted email addresses by recipients;
  4. Messages containing key fields that can be defined as spam by an anti-spam device or by a mail filter;
  5. Messages with fake or invalid headers, messages with fake or invalid domain names, and messages that are processed technically without showing any information about the source of the message. Mail with fraudulent address information;
  6. Using, relaying, or sending mail through Internet devices of third parties without consent;
  7. Subject lines or messages containing false, misleading or false information;
  8. The subject or content with sensitive words, in violation of national laws and regulations.

How to improve the success rate of sending emails and reduce being identified as spam

As you can already see from the above, most messages sent through the system trigger clauses 5 and 6 of the spam rule. The solutions are as follows:

  1. Try not to use your own post office server. Because the IP of the self-built post office server is not trusted by the major post office system, especially the new post office system. You are advised to use a well-known SMTP port, such as Tencent enterprise email (free), NetEase enterprise email (free), and Outlook.
  2. The email address field of the sender must be the same as the suffix of the mailbox. For example, if the sender’s email address is [email protected] and the SMTP user name is [email protected], the success rate of sending an email is very low and it is easily identified as an email sent by unauthorized use, relay, or a third-party Internet device.
  3. Add the IP address of the sender server to the SPF. For details about SPF, see: What is SPF? For example, if the IP address of the WordPress server is, you need to set the SPF record in the domain name of the mailbox (Tencent enterprise mailbox is used as an example) : V = spf1 ip4: include:spf.mail.qq.com ~ all
  4. Do not use the names such as advertise, notify, notice, admin, webmaster, and System for sending emails.
  5. Do not include sensitive keywords in your email.

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