Tuesday, April 2, 2019

How to send emails and avoid them being classified as spam?





This is a canonical question about how to handle email sent from your server being misclassified as spam. For additional information you may find these similar questions helpful:







Sometimes I want to send newsletters to my customers. The problem is, that some of the emails get caught as spam messages. Mostly by Outlook at the client (even in my own Outlook 2007).



Now I want to know what should be done to create "good" emails. I know about reverse lookup etc., but (for example), what about a unsubscribe link with an unique ID? Does that increase a spam rating?


Answer



Be sure that your emails don’t look like typical spam emails: don’t insert only a large image; check that the character-set is set correctly; don’t insert “IP-address only” links. Write your communication as you would write a normal email. Make it really easy to unsubscribe or opt-out. Otherwise, your users will unsubscribe by pressing the “spam” button, and that will affect your reputation.



On the technical side: if you can choose your SMTP server, be sure it is a “clean” SMTP server. IP addresses of spamming SMTP servers are often blacklisted by other providers. If you don’t know your SMTP servers in advance, it’s a good practice to provide configuration options in your application for controlling batch sizes and delay between batches. Some mail servers don’t accept large sending batches or continuous activity.




Use email authentication methods, such as SPF, and Domain Keys to prove that your emails and your domain name belong together. The nice side-effect is you help in preventing that your email domain is spoofed. Also check your reverse DNS to make sure the IP address of your mail server points to the domain name that you use for sending mail.



Make sure that the reply-to address of your emails are a valid, existing addresses. Use the full, real name of the addressee in the To field, not just the email-address (e.g. "John Doe" ) and monitor your abuse accounts, such as abuse@example.com and postmaster@example.com.


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