Using ISPConfig for Email-Only Hosting with Billing Add-on (No Web/DNS)

Hello everyone,

I’m planning to deploy a setup using ISPConfig specifically for email hosting services only, and I would like some guidance from the community.

My goal is to:

• Use ISPConfig to manage mailboxes, domains, and email accounts only
• Integrate the ISPConfig Billing module to automate customer provisioning (orders → email account creation)
• Sell email hosting plans (storage-based or mailbox-based)
• Allow users to manage their email (via webmail like Roundcube, etc.)

Important:
I do NOT want to provide:

• Website hosting
• DNS hosting (if possible)

This would be a dedicated email hosting platform only.

My questions:

1. Is it possible to install and configure ISPConfig in a way that only email services are active (Postfix, Dovecot, etc.) without web hosting features?
2. Can the ISPConfig Billing add-on be used effectively for:
   • Creating email domains and mailboxes automatically after purchase
   • Managing quotas (per mailbox or per domain)
3. Is there a recommended setup or best practice for:
   • Email-only environments (single server vs multi-server)
   • Required services (Postfix, Dovecot, Amavis/SpamAssassin, etc.)
4. Can DNS be fully external (e.g., Cloudflare), while ISPConfig handles only mail?
5. Are there any limitations or drawbacks when using ISPConfig in this “email-only SaaS” model?

My use case:

I’m building a small email hosting business (similar to Zoho Mail / ProtonMail-style offerings), where customers:

• Purchase email plans
• Get mailboxes automatically provisioned
• Access webmail and SMTP/IMAP

No website hosting or traditional shared hosting involved.

If anyone has experience running ISPConfig this way or has documentation or examples, I would really appreciate your insights.

Thank you in advance!