Email Server setup

If you want to setup an server mass email campaigns, it must to have following network settings configured for email server. Almost all these configurations are used to authenticate “Sender’s” identity in one way or the other.

1. Reverse DNS lookup
Email server receiving email, try to lookup your domain based on the IP address sending the emails to validate that emails are in fact being sent from a server which belongs to the domain in the sender or return path. For this lookup to be successful, all the IP addresses sending emails shall loop back to your domain name (reverse DNS lookup). rDNS can be configured by having a PTR record pointing to your domain. Generally, your ISP will be able configure the PTR record.

2. SPF TXT record
SPF is another way of authenticating email sender identity.
Refer to http://www.openspf.org/ for more details about SPF and help in setting up SPF record. This TXT record will need to created with your DNS provider.

3. DKIM and Domain keys
Terms DKIM and domain keys are mostly used interchangeably, however they are slightly different and it is preferred to have both records. Big email providers specifically Yahoo and GMail like the
emails sent from domains with DKIM and domain keys. Method of generating these varies based on the email server like Zimbra or Mailenable. Mostly, mail server vendors will provide utility to generate private and public keys. Private key shall be hosted on email server and public key will be hosted by email server DNS provider.
Refer to http://DKIM.org and http://domainkeys.sourceforge.net/ for further details.

4. Address record for mail server
Mail server shall be configured to send emails from a domain or subdomain and never a IP address. Emails sent directly from IP address directly are generally considered as SPAM. You shall have “A” record configured for your mail server with the DNS provider.

5. No Open relay and allow only authenticated sender
Do not allow mail server to act as open relay. Open relay could be used by SPAMmers to send spam, which might result in blacklisting of your IPs. Server shall only authenticated user to transmit emails.

6. Use Multiple Static IPs
You shall always use only static IP address to transmit emails. It is preferable to have multiple IPs to transmit emails for effective email throttling and reduce the probablity of being considered as spammer.

7. Autheticated sender
You can also consider becoming an authenticated sender. You would need to work with one of the email accreditation vendors. Returnpath.com and Suretymail.com are two reputed ones to the best of my knowledge.This could be an expensive proposal based on your volume of emails.

8. Install SSL on mail server
Email server shall have SSL certificate installed, preferably from a well known CA

Additionally, you shall subscribe to services provided by mxtoolbox.com and/or DNSLookUp to monitor server’s health and blacklisting.

It is very important to play by the rules if you want to have high delivery rates and prevent blacklisting.

December 11th, 2009|Technical|