There are two ways to integrate Sendgrid SMTP

Option 1

1. Create an API Key with at least “Mail” permissions from https://app.sendgrid.com/settings/api_keys
2. Email address: Email address from where you want to send message.
3. SMTP host:  smtp.sendgrid.net
4. SMTP username: apikey
5. Password: The API key generated in step 1.
6. SMTP port: 465
7. SMTP type : SSL

First of all, login to your WordPress dashboard. In the left menu select Plugins – Add New.

Here is the full video instruction of how to setup Sendgrid SMTP API

Option 2

1. SMTP host: smtp.sendgrid.net
2. SMTP username: your sendgrid account username
3. Password: your sendgrid account password
SMTP port: 587
SMTP type : TLS