Default Forge server name affecting emails going to spambox?

Hi,

I have installed WordPress on Forge. I'm having some issues with email going into the spambox.

Looking at the email I see some issues where it's sending the emails from .localdomain. See some snippets of the email data below. (I have obfuscated some data)

spf=neutral (google.com: xxx.xxx.xxx.xxx is neither permitted nor denied by best guess record for domain of [email protected]) [email protected]
Return-Path: <[email protected]>
Received: from deep-truth ([xxx.xxx.xxx.xxx])
by mx.google.com with ESMTPS id e189si2893052qkc.64.2019.08.23.16.07.55
.
.
Received-SPF: neutral (google.com: xxx.xxx.xxx.xxx is neither permitted nor denied by best guess record for domain of [email protected]) client-ip=xxx.xxx.xxx.xxx;
Authentication-Results: mx.google.com;
spf=neutral (google.com: xxx.xxx.xxx.xxx is neither permitted nor denied by best guess record for domain of [email protected]) [email protected]
Received: from deep-truth.localdomain (deep-truth.localdomain [127.0.0.1]) by deep-truth (8.15.2/8.15.2/Debian-10) with ESMTP id x7NN5tdu018123 for <[email protected]>; Fri, 23 Aug 2019 23:05:55 GMT
Received: (from forge@localhost) by deep-truth.localdomain (8.15.2/8.15.2/Submit) id x7NN5ttr018122; Fri, 23 Aug 2019 23:05:55 GMT

Now something I noticed is that it's using the server name when creating a forge instance. So in this case it's deep-truth which is a random name that is created by forge. Running hostname on the CLI outputs deep-truth. Should this be the name of the domain?

Looking at the /etc/hosts file. I also see the following:

127.0.0.1 deep-truth.localdomain deep-truth
127.0.0.1 localhost

Does anyone have experience with this?