Follow the steps below to set up Sendmail for Dyn’s Email Delivery.

Additional steps for setting up Sendmail on CentOS are included at the end of this page. More information about Sendmail can be found on their site.

Integrating Sendmail with Dyn’s Email Delivery

1. Add two lines to the file sendmail.mc.

The first line tells Sendmail to send outbound emails through the smtp.email.dynect.net relay.

The second line indicates that sending email will require authentication.

define(`SMART_HOST',`smtp.email.dynect.net')
FEATURE(authinfo)dnl
2. Build sendmail.cf. m4 sendmail.mc > /etc/sendmail.cf
3. Add a safe subdirectory to where your configuration files (sendmail.mc and sendmail.cf) are located. Example: /etc/mail/authinfo
4. Add a file in the safe subdirectory authinfo from step 3 with this line:
AuthInfo:smtp.email.dynect.net "U:<user>" "I:<user@host.com>" "P:<password>" "M:LOGIN PLAIN"
ReplaceĀ <user>, <user@host.com>, and <password> with your information. "M:LOGIN PLAIN" tells Sendmail to send the authentication information in plain text.
If you get authentication errors, you may need to install the cyrus-sasl-plain RPM, which contains support for PLAIN and LOGIN authentication schemes.
5. Build the authinfo file. makemap hash /etc/mail/authinfo < /etc/mail/authinfo
6. Restart Sendmail.
7. Make sure the address you use as the FROM: email address is set in Email Delivery as an approved sender.

Setting Up Sendmail on CentOS

1. Install Sendmail. yum install -y sendmail sendmail-cf
2. Edit /etc/mail/access as shown: AuthInfo:smtp.email.dynect.net "U:root" "I:" " " "M:LOGIN PLAIN"
3. Build the Access Database. makemap hash /etc/mail/access.db < /etc/mail/access
4. Add the webserver user to the trusted users folder path as shown: /etc/mail/trusted-users
5. Edit /etc/mail/sendmail.mc as shown: define(`SMART_HOST',`smtp.email.dynect.net)dnl
6. Make the sendmail.cf file as shown: m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf
7. Restart Sendmail.