Freshdesk uses Sendgrid as its email service provider to send and receive emails. If you choose to use your own mail servers instead of the Freshdesk server, you can use the custom mail servers feature.
Here is a youtube video on setting up a custom mailbox in Freshdesk to help you get started.
As an administrator of your Freshdesk account, you can set up custom email servers by adding your mail server's IMAP and SMTP details to your Freshdesk Account.
Navigate to Admin from the menu bar. Select Channels and click on Email.
Under the list of support emails, click on Edit corresponding to your email address.
Scroll down and select the ‘Use your existing support email’ option to configure your custom mail server settings.
Note : If you have subscribed to the current plans, this feature can be accessed through the Growth plan. Alternatively, if you have subscribed to previous plans of Freshdesk, the feature is available through the Blossom plan.