# Sendmail

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.

> \[!CAUTION]
>
> 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**

> \[!CAUTION]
>
> 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!

```bash
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

```bash
define(`SMART_HOST', `smtp.sendgrid.net')dnl
FEATURE(`access_db')dnl
define(`RELAY_MAILER_ARGS', `TCP $h 587')dnl
define(`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')

```bash
cd /etc/mail
m4 sendmail.mc >sendmail.cf
makemap hash access.db < access
```

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

```bash
/etc/init.d/sendmail restart
```

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

```bash
service sendmail restart
```

Now, your Sendmail configuration is optimized for using SendGrid's SMTP service, ensuring efficient and reliable email delivery.