Email Filtering, Bouncing, and Blocking

When you send an email, it starts out on a server. If you use an Email Service Provider, it sends your email to Internet Service Providers such as AOL or Yahoo! and email programs such as Outlook. These programs and service providers try to sort the email and send only the good email to their customers. When something looks unwanted, they send it to a junk folder or return to the sender. The process is pictured in Figure 11.1.
Figure 11.1 Email delivery is a complex process.
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Email delivery can be interrupted or rerouted at many points in the delivery process, even when the email reaches an individual’s computer. You can’t control all the delivery issues you’ll encounter, but understanding the challenges inherent in the delivery process is the first step toward maximizing your email delivery. Understanding the process also allows you to recognize errors and correct the ones that are possible to improve.
Understanding the technical definitions of bounced, blocked, or filtered isn’t as important as determining the underlying cause of these delivery issues. All of these words mean that the email failed to reach the recipient’s inbox. The following sections explain the various underlying issues that cause emails to go undelivered, no matter which technical category they fall into.
(Sometimes you can tell when an email is undelivered and ...

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