How to Keep Email Out of the Spam Folder?

Overview

The article contains instructions to make sure other servers or networks do not flag your email as spam. Spam should not be sent by your server. To learn how to prevent emails from ending up in the spam folder, read on.

Use email authentication

DKIM and SPF

DKIM (DomainKeys Identified Mail) and SPF (Sender Policy Framework) authentication help verify that email comes from a trusted sender. 

An email validation technology called DKIM can identify emails that have been spoofed. It allows your mail server to ascertain whether the email from that domain has been authorized by the domain administrator. Your mail server utilizes the digital signature in the email to verify the sender’s public key in their DNS record.

To combat email spoofing, SPF employs DNS records. When an email message contains fake sender addresses, SPF checks the DNS record for the sender’s domain to identify the change in the email’s header.

On servers running CentOS 7, CentOS 8, or AlmaLinux OS 8, you may notice a named warning regarding the absence of SPF resource entries on DNS.

Because RFC 7208 deprecated SPF records, this warning does not apply to CentOS 7, CentOS 8, or AlmaLinux OS 8 systems. TXT records are used instead of SPF records on CentOS 7 and 8 servers.

Both Red Hat 7.1 and CentOS 7.1 include bind-9.9.4-23.el7, an improved version of BIND that conforms with RFC 7208. To solve this problem, upgrade your operating system to a version including the most recent version of BIND. Read the Red Hat Bugzilla case regarding SPF record problems for additional details.

DMARC

DMARC (Domain-based Message Authentication, Reporting, and Conformance) is a technological specification designed to decrease the possibility of email-based abuse. A DMARC policy utilizes DNS to validate that an email message has a valid DKIM and SPF record. A DMARC also checks if the From: header matches those records.

To protect users from spam email, several email networks ask you to employ a DMARC policy. Your server must adopt a DMARC policy to avoid email rejections or spam flags within these networks.

Server PTR record configuration

An IP address and a domain name can be mapped using a PTR record. An A record in reverse is comparable to a PTR record. Set your server’s hostname to be used in the PTR record for its IP address. Make sure your server’s hostname is used in the PTR record for the IP address you’ve configured Exim to utilize.

Example of A record:

server:~ root$ dig mx1.cpanel.net +short
208.74.121.68
server:~ root$

Example of PTR record:

server:~ root$ dig -x 208.74.121.68 +short
mx1.cpanel.net.
server:~ root$

Spam and other networks

If email from your server is marked as spam by email networks like Gmail, Yahoo, or Outlook, you need to look into the matter and find a solution. If you have resolved a spam issue on your server or have acquired a new IP address that has sent spam in the past, you need to notify the remote network. Make sure you review the email networks’ policies regarding bulk senders.

Best practices to send bulk email

• Send all bulk emails from the same IP address.
• Use the same email address in your emails’ From: header.
• Check to see whether your email complies with RFC 5322.
• If you use HTML in your email, be sure it adheres to HTML standards.
• Make sure that the contents of your email are relevant to the subject of your email.

Related Article: Steps to Add SPF, DKIM, and DMARC Records On Your Domain

 That’s how you can keep your email out of the spam folder.