How to Create a Custom Agent

What You Will Learn

This guide walks you through creating a custom agent — an AI agent tailored to your exact workflow, living at its own email address. Available on the Premium plan and above.

What makes a custom agent different from help@via.email?

A custom agent ships with your standing brief already loaded. You stop re-explaining tone, output shape, and guardrails on every send. help@via.email stays better for one-off experiments; custom agents win when the same class of work shows up every week.

Before You Start

You need a via.email account on the Premium, Business, First, or Charter plan. If you are on the Free or Economy plan, you can upgrade by emailing subscribe@via.email.

Step 1: Compose the Creation Email

• To: create@via.email
• Subject: The name of your agent (e.g., "Translate to French")
• Body: Your agent instruction — describe what the agent should do, how it should respond, and any rules it should follow

Step 2: Write a Good Instruction

The instruction is the most important part. It tells the agent exactly how to behave. Think of it as briefing a new assistant.

Tips for writing effective instructions:

• Be specific. "Translate the email body into formal French" is better than "Translate to French."
• Define the output. "Reply with the translation only, no commentary" sets clear expectations.
• Include rules. "Always preserve the original formatting" or "If the input is unclear, ask for clarification."
• Give examples if helpful. "For a meeting invite, translate the subject line and all body text."

Your instruction will be automatically polished by AI to make it more effective. You will see both your original and the polished version in the confirmation email.

Step 3: Attach Context Files (Optional)

On the Business plan and above, you can attach reference files when creating an agent. These give the agent permanent context — for example:

• A brand style guide for a writing agent
• A template document for a report-generating agent
• Sample data for an analysis agent

Simply attach the files to the creation email.

Step 4: Receive Your Agent

Within seconds, you will receive a confirmation email with:

• Your agent's email address (auto-generated from the name, e.g., translate.to.french@via.email)
• A summary of what the agent does
• The polished instruction

Your agent is now ready to use. Email it just like any other agent.

How Agent Addresses Work

via.email generates the agent address automatically from the name you provide:

• Spaces become dots
• All characters are lowercased
• Special characters are removed
• If the address already exists in your account, a number is appended

You cannot manually choose a custom email address, but you can influence it through your agent's name.

Some email addresses are reserved for system commands and cannot be used. See via.email/rea for the full list.

Agent Limits

The number of custom agents you can create depends on your plan:

• Premium: Up to 5
• Business: Up to 15
• First: Up to 50

You can check your current agent count by emailing check@via.email.

Related reading

• Small law firms automate contract email without new software
• Freelancers navigate contract chaos through email intelligence
• Property managers extract lease terms via email

For quick answers, see our FAQ.