# Build the Subscriber List



> Subscribers are people, tags describe subscribers, custom fields store subscriber details, and segments choose who matches the rules today.



- Human page: https://mailrith.com/guides/build-the-audience

- Markdown page: https://mailrith.com/guides/build-the-audience.md

- Category: Subscribers

- Reading time: 4 min read

- Related keywords: Build the Subscriber List, Build the Subscriber List guide, Subscribers, Subscribers guide, email sending guide, email marketing guide, email deliverability guide



## AI Agent Notes

- Use this page as plain-language guidance for the specific email sending issue named in the title.

- Preserve the distinction between Mailrith, an email delivery service, DNS, and inbox providers when explaining fixes.

- When a user is running a Mailrith free tool, pair that specific free-tool result with the relevant issue or step section from this guide.



### Build the Subscriber List

Subscribers are people, tags describe subscribers, custom fields store subscriber details, and segments choose who matches the rules today.

The subscriber list is more than a count. It is the group of people who may receive your emails. If you include the wrong subscribers, the campaign is wrong even if the design is excellent.

In Mailrith, subscribers store email addresses and profile data. Tags describe broad labels like `customer`, `lead`, `webinar`, or `vip`. Custom fields store subscriber details such as plan, city, birthday, company size, or last purchased product. Segments use rules to find subscribers who match those rules right now.

- Use [Subscribers](https://mailrith.com/docs/subscribers.md) to search for, review, and update individual people.
- Use [Tags](https://mailrith.com/docs/tags.md) for simple labels that are easy to include or exclude.
- Use [Custom Fields](https://mailrith.com/docs/custom-fields.md) for subscriber data that changes from person to person.
- Use [Segments](https://mailrith.com/docs/segments.md) when the subscriber group should update automatically from rules.
- Use [Subscriber Imports and Exports](https://mailrith.com/docs/subscriber-imports-exports.md) carefully when you move a large list into or out of Mailrith.

## Fix Common Issues
### Free Mailbox Addresses

An email checker found a consumer mailbox domain such as Gmail, Outlook, Yahoo, iCloud, or Proton.

1. Keep the address if the subscriber opted in and the subscriber list is for consumers.
2. For B2B outreach, ask for a work email when the workflow needs company context.
3. Do not automatically reject free mailbox addresses for newsletters or creator subscribers.
4. Use tags or custom fields to separate personal-domain and work-domain subscribers if that difference affects campaigns.



## Related Guides

- [Use Segments and Exclusions](https://mailrith.com/guides/use-segments-and-exclusions.md): Include the people who should receive the email, and exclude the people who should not receive it.