If you are using Sendgrid for your email campaigns, you can connect your Sendgrid account to Klenty to send emails.
To do this, select your email provider as 'Other SMTP/IMAP'.
In the SMTP details, enter the username as 'apikey' (This is the default username given by Sendgrid.) and generate an API key which is the password.
The IMAP details is the same detail as your email service provider (Gmail, Outlook, or Office 365).
Note: You can find your SMTP port number from within your Sendgrid account.
Here's a walkthrough from Sendgrid on sending emails from SMTP.