Very common problem among hosting problems facing by hosting providers these days is issue of user mail not delivering on other server end. It make both end people annoyed and frustrates the server administrator also. As, there is no clear indication for the reason of mail failures. Now, here i will give you tips to make your mail server more reliable and also give you tips about mailing lists used by end users. Here, thing to keep in mind is that you cannot control remote mail servers incoming email policies.

1. Do you look like a spammer?

You have to take a look at your mails sending in bulk amount and consider whether it is spam or not. You can say out of lakh people at least couple hundred are going to make spam complaints against you as mostly are spammy in nature.

2. Proper management of your mailing lists:

As your mailing list grows in size there will be going to have some email addresses which are not in use or invalid or do not want to receive your email any more. If you think to make a subscriber stick to you by hiding the Opt-out link, they will going to mark it as spam. So, it will be better for you put that opt-out link in your reminder while sending emails to your clients mentioning the reason that why you have send this message.

Ex:This notification is regarding being client of us and you have purchased BLAH-BLAH product on and requested to receive emails.

If you do not want to receive emails further, Kindly
click here

It will reduce your mailing list from unwanted email addresses and also from those who do not want to receive your mails too.

3. Limitations on server outgoing mails:

If you are a hosting provider then it is not possible to categorize users that are doing bulk emailing. In such case you want to make boundation on users that how much emails they can send in shared hosting environment as any single user can affect rest of the users on same server. You can limit outgoing emails by two ways:

a). Through WHM: On 11.28 versions or upper you can do through WHM >> "Server Configurations" >> "Tweak Settings" >> "Max hourly emails per domain"

b). through exim.conf file: You can set



4. Tighten up your mail server:

If you want to make your server targeted as spam hack, the best and easy way is allowing PHP nobody mail. As we all know every time a PHP script sends mail using mail() function, it uses user as 'nobody' and by default root/system user is user 'nobody'. It will allow a rouge mailing script to send unlimited emails through your server and it results in server blacklisted. You can avoid this by using suPHP and made changes in WHM >> "Server Configuration" >> "Tweak Settings"

You have to turn on the SMTP Tweak


/scripts/smtpmailgidonly on


You can also go for sender verification settings, which you can set through WHM >> "Server Configuration" >> "Exim Configuration Editor"

5. Use only SMTP to send mails:

It is very easy to use SMTP, as it used by mostly all mailing software’s. You have to use SMTP settings for mailing software’s which use correct username, password and email address.

6. Use SPF Records and Domain keys:

To authenticate your email on other email server you have to use SPF and DKIM records, so that they can realize the mail coming to them are from your server and not spoofed. This will better help to deliver mails to email services like. Gmail, MSN, Yahoo, Hotmail.

7. Regularly monitor your server IP's:

It is quite easy to get blacklisted on any RBL's. You have to regularly check your IP blacklisted or not and take action to delist it.

8. Do not use same IP for email:

Emails are sent through the same IP which is used as main IP for server by default. You have to use different IP's for the account who sends huge amount of emails, so that they will not affect other clients on your server.

9. DNS records should be properly setup:

You have a proper setup for your mail records like if you mail server named as "" and it is pointing to IP "" then its reverse DNS record should also match. It means PTR of "" IP should be "".

These DNS records should be according to EHLO/HELO name provided by your MTA(EXIM). This can be changed in "/etc/mailhelo" through WHM >> "Exim Configuration Editor".
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