If you're looking to enhance your email delivery capabilities with SendGrid and Sendmail, you're in the right place. Setting up Sendmail to work seamlessly with SendGrid's SMTP service can greatly improve the reliability and efficiency of your email communications.
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. For more information on configuring sendmail for SASL support, check the official documentation.
Set the authorization credentials in /etc/mail/access
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!
_10AuthInfo: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
_10define(`SMART_HOST', `smtp.sendgrid.net')dnl_10FEATURE(`access_db')dnl_10define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl_10define(`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')
_10cd /etc/mail_10m4 sendmail.mc >sendmail.cf_10makemap hash access.db < access
On older distros, you can run restart sendmail like so:
_10/etc/init.d/sendmail restart
If, however, you're using a newer version, do the following to restart:
_10service sendmail restart
Now, your Sendmail configuration is optimized for using SendGrid's SMTP service, ensuring efficient and reliable email delivery.