Cannot Access Webmail HTTP ERROR 500

Hello,

I am currently having an issue accessing my site’s webmail. I set up an email for the domain, enabled DKIM, and issued an SSL for the mail.mydomain.com.

When I go to Email → Access Webmail, I get this response:

This page isn’t working
panel.mydomain.com is currently unable to handle this request.
HTTP ERROR 500

I made sure that the PostFix service is on and I also restarted it but it did not fix the issue.

Anyone know what might be causing this or how to fix it? The site is currently set up on a DigitalOcean droplet.

Thank you in advance!