Open your modules page, find the SMTP module, and configure it with the following settings:
- SMTP Server - smtp.sendgrid.net
- SMTP Port - 587
- Use Encrypted Protocal - No. If you want encryption choose “Use SSL” and set SMTP Port to 465
- Username - SendGrid Username
- Password - SendGrid Password
To use the Swift Mailer module, install a version of this module that is compatible with your version of Drupal.
Configuration for this module is largely the same as above.