Possible to setup Jira login-free portal without auto-created accounts?

[Team Platform Admin]

Is it possible to enable login-free portal without allowing auto-created user accounts?
We already have email setup to auto-create accounts when our service desk project receives an email and it looks like the login-free portal is tied to this.
We'd like the ability to allow account creation via requests raised by email while disallowing account creation via login-free portal. 
I've looked through the setup and docs and did not find a clear way to achieve this setup. Any guidance on getting this setup would be appreciate.

[Christopher Yen]

Hopefully this documentation provides what you're looking for,

"If you want a portal on your JIRA site to be login-free, a JIRA admin needs to allow login-free portals at the global level. Then, project admins can choose whether to use a login-free portal, or restrict the portal to people their team adds to the project. Learn more about permissions.

To start using the login-free portal, follow these steps:

1. In the global settings, a JIRA admin allows login-free portals on the site. This doesn’t automatically turn it on for all the portals, it just makes it an option for projects on the site. 
   To do this, go to > Products > JIRA Service Desk Configuration > Customer permissions. 
   • For Can customers create their own accounts? choose Yes. (maybe No?)
   • For Can customers access and send requests form the help center without logging in? choose Yes.
2. In the project settings, a project admin allows anyone to send requests to the project.
   To do this, go to Project settings  > Customer permissions (or Project settings > Channels > Customer permissions in next-gen projects).
   • For Who can access the portal and send requests to %your_site_name%?, choose Anyone.
3. If you want customers to be able to read your knowledge base without logging in and find articles via search engines, verify your knowledge base settings.
   To do this, go to Project settings > Knowledge base.
   • For Access > Viewing, make sure Anyone can read articles is selected.

"

(https://confluence.atlassian.com/servicedeskcloud/blog/2017/04/introducing-the-login-free-portal-for-jira-service-desk-cloud)

Another route might be to set up an issue collector to embed in another site for your customers? I believe that will be a login free way of submitting issues as well.