Sendmail

To route Sendmail through SendGrid's SMTP service, configure SASL authentication and set SendGrid as the Smart Host. The following steps show how to configure the credentials, define the Smart Host, and restart Sendmail.

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Danger

Sendmail requires libsasl in order to properly send authentication requests to SendGrid servers. The saslauthd server daemon is not required unless you plan to receive authentication requests to the same server.

Set the authorization credentials in /etc/mail/access

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Danger

We have had reports that some customers have needed to install cyrus-sasl-plain in order to avoid authentication issues as well. We have not validated this requirement, so please make sure your system administrators, Ops, and/or InfoSec people approve this change before you make it!

AuthInfo:smtp.sendgrid.net "U:apikey" "P:yourAPIKey" "M:PLAIN"

Define the Smart Host in /etc/mail/sendmail.mc You should add these lines just after the commented \#dnl define('SMART_HOST', 'smtp.your.provider')dnl line in the file

1define(`SMART_HOST', `smtp.sendgrid.net')dnl
2FEATURE(`access_db')dnl
3define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl
4define(`ESMTP_MAILER_ARGS', `TCP $h 587')dnl

Update sendmail.cf and access.db files

(You will need to run these commands as 'su' or 'root')

1cd /etc/mail
2m4 sendmail.mc >sendmail.cf
3makemap hash access.db < access

On older distros, you can run restart sendmail like so:

/etc/init.d/sendmail restart

If, however, you're using a newer version, do the following to restart:

service sendmail restart