More Sendgrid user support for SMTP set up can be found here.
Sendgrid credential overview:
1. Host
smtp.sendgrid.net
2. Port
587
3. Username
Your email address.
4. Enable SSL
Choose to enable SSL.
5. Password
The password you use to log into your mail account.
6. Email Address
Your email address, as above.
7. Send Test Email
This area allows you to test your SMTP server. Enter an email address to send the test email address to (can be the same as your email address set above).
Once you enter the email address, press Send Test. You will see the text area at the bottom of the page start showing some details.
If Successful:
You will see a green message with "The SMTP server successfully configured".
You will receive an email to the Send Test Email address with the subject "Custom SMTP Success".
If Fails:
You will see a red message with "The SMTP server recorded an error code xxx".
If you get this message, there is something wrong with the SMTP details entered.
Check your settings and try again.
You must press the Save SMTP Settings button after entering the details. If you do not save, the settings will be lost.
If you have attempted to enter new SMTP settings in error, press the Cancel button to cancel all changes.
Once you save, you will be taken back to the Sharing Settings screen, where you can see that the Custom SMTP Server is now "configured".