Here are some recommendations for sending emails and mail server settings which will prevent server from blacklisting and also ensure that your E-mails are delivered to intended remote users. To maintain your server reputation and keep email out of the spam folder, you will have to enforce all these practices.

 

Have a reverse DNS entry :

A Reverse DNS entry (FQDN) must exist for the delivering server and hostname should resolve to the
same IP address. The PTR record helps to identify the source of emails and authenticity of the source server.

SMTP Authentication and Sender Policy Framework/Domain Keys :

Its highly recommended to publish an SPF record, and signing with DKIM or DomainKeys so contact with your server admin/host and make sure your email server supports these protocols(DKIM, SPF, Sender-ID and Domain Keys) and that they are properly implemented. These are essential in preventing others from spoofing your mail server IP and using / damaging its reputation.

If you are using an email client then make sure that the “Server requires SMTP Authentication” option is checked.

 

Unsubscribing and Opt-out :

The recipient must be given a fast and simple opt-out option for receipt of the mass mail (newsletter, advertising etc.).
A user must be able to unsubscribe from your mailing list through one of the following means:

* A link in the body of an email leading users to a page confirming his or her unsubscription (no input from the user, other than confirmation, should be required).
* By replying to your email with an unsubscribe request.

 

Password Strength and Periodic change :

Choose strong passwords for email accounts which contains a combination of upper and lower case letters, numbers and special characters. Keep changing them periodically as it will mitigate the risk of compromise and brute force attacks.

 

Your server and desktop security :

Install and maintain an effective antivirus / anti-malware applications across all of your servers and desktops
to help prevent their compromise. Do scan your web contents and email messages and make sure that those do not contain
phishing or malware hosted server’s link.

Avoid spam trigger words and acceptance of un-routed emails on catch all address:

Avoid using words tagged by spam filters, such as “vi#a$,” “F$$k,” “unsubscribe,” “sales,” etc.
The default or catch-all address is the one to which all e-mails, addressed to a non-available or mistakenly entered email account at your domain name are routed to. In case someone sends an email to xyz[@]domain.tld and you do not have such address, the catch-all option could forward this email to your default email address or any other remote mail server. Do not accept and forward such email messages to catch-all address.

 

Blacklisting status [RBL ]:

 

Make sure that your server is not on any of RBL listing. You can check this information at DNSBL.info or Email Blacklist Check – See if your server is blacklisted sites. If you find server IP listed in any of those DB, then apply corrective actions with the help of hosting support and submit review/delisting request to appropriate RBL organization team.