What's the right version for me or my customers?

The SB version has a single user account architecture more suited for single organizations or businesses. You can have multiple administrators with different roles but administrator accounts are not isolated.
For example, if you have two Newsletter editors they can both see and edit the same newsletters.
The MB version is technically identical to SB but with a different licensing.
The ESP version allows you to create multiple, completely isolated and independent user accounts.

A single business or organization that does email marketing.
- The organization may have different departments and each department may have its own mailing lists (and Sender profile settings).
- A subscriber can of course be subscribed to several lists.
- Different roles can be assigned to various administrators. Like, reports-only user, newsletter editor, list manager and more. But there is no data isolation among these administrators.
IT professionals that want to send campaigns on behalf of their clients.
- You can use a different Sender profile (sender details, sending method, landing pages, etc) for each client.
- You can share an encrypted link with your clients to access a campaign summary report.
- But you may not give login access to a client (in case you manage lists from many different clients).
Here is the demo.

IT professionals that offer Email marketing as a Service to their clients.
You do a single installation of the app under your own domain. Then you open User accounts for your clients.
Each user account feels like and has practically all features of nuevoMailer SB.
These accounts are completely isolated (also at the database level). There is no data sharing between user accounts.
Administrator roles are not supported. The client has only one login email.
Your clients design their newsletters, manage lists and send campaigns.
Only some higher level system tasks are reserved for you as "master administrator" (account management, email plans, smtp settings etc).
Of course you can still do all the work or divide the tasks with your client.
Charging a fee to your clients is optional.
The ESP version may also be suitable for larger organizations with different and independent departments or lines of businesses.

ESP Demos

Master administration panel

This is where you login to manage users and orders, create email plans, edit settings and monitor the system.

This is where you users login to create newsletters, campaigns, autoresponders and manage their mailing lists.

Having different standalone installations at your customers' domains. You can do that either with the SB or the MB (1 year subscription license).
You can still do all the work or share some tasks with your customer. You can open different administrators accounts with different roles.
Consider this model when a customer has special requirements about data ownership and access.
It is cost-effective; you have 50% discount for each additional SB license that you order.
If you plan to have many installations or want the freedom to install anytime, anywhere consider the MB version (1 year subscription license).

With all versions,

The concept of "tracking domain” can be applied so that newsletter links point to the domain of your choice without actually having the mailer installed at that domain.