Email Relay Issue JSON.parse

What type of hardware are you using: VPS bought online
What YunoHost version are you running: 12.0.17
What app is this about: GoToSocial

Describe your issue

I set up a VPS a few months ago and installed GoToSocial. I set up an email relay and everything appeared to be functioning as expected.

I recently tried to onboard a friend and realized that the email function wasn’t working.

I sent myself a test email and got

PARSING_ERROR: SyntaxError: Unexpected token ‘<’, “
<h”… is not valid JSON

On an unrelated note, I also fired up a IceShrimp server wondering if some friends and relatives might like such a thing. I set up the email relay there and got something along the same lines:

JSON.parse: unexpected character at line 1 column 1 of the JSON data
undefined

As always, thanks for any help here.

Share relevant logs or error messages

Available if needed?