Instantly Bulk Mailbox Config

Stop copy-pasting signatures, sending limits, and warmup settings into your Instantly mailboxes one by one. This actor updates hundreds of mailboxes at once from a single template, with optional per-mailbox personalization.

Built for cold email agencies and senders running 50 or more mailboxes on Instantly.ai.

Only the fields you fill in get changed. Everything else stays.

How to use

1. Install the Cookie-Editor Chrome extension.
2. Log into Instantly. On app.instantly.ai, click the Cookie-Editor icon, then Export, JSON.
3. Paste the JSON into the Instantly cookies field.
4. Choose which mailboxes to target.
5. Fill the fields you want to change.
6. Optional: turn on Dry run for a preview before applying.

Cookies last roughly a week. Re-export from Cookie-Editor if you get an auth error. Or use your Instantly email and password in the fallback fields. SSO and 2FA accounts must use cookies.

Mailbox filters

Choose which mailboxes to update:

• All mailboxes in the workspace
• By domain, e.g. acme.com matches jane@acme.com, bob@acme.com
• By tag, matches mailboxes that carry any of the tag names you provide
• By explicit email list, exact addresses only

What you can change

Leave any field blank to skip it. Empty fields are not touched on the mailbox.

Mailbox identity

• Signature (HTML, supports personalization)
• First name
• Last name
• Reply-to address

Sending behavior

• Daily sending limit, max emails per day
• Sending gap, minimum minutes between sends
• Custom tracking domain
• Inbox placement test limit

Warmup

• Warmup daily limit
• Warmup increment
• Warmup reply rate
• Warmup custom filter tag
• Enable slow ramp

Warmup advanced

• Weekday only, only send Monday to Friday
• Read emulation, simulate recipient reading the email
• Warm custom tracking domain
• Open rate (%)
• Spam save rate (%)
• Important rate (%)

Personalization

Signature, first name, last name, and reply-to support placeholders that get filled in per mailbox. For an example mailbox jane@acme.com:

• {{email}} becomes jane@acme.com
• {{first_name}} becomes the existing first name on the mailbox
• {{last_name}} becomes the existing last name on the mailbox
• {{domain}} becomes acme.com
• {{local_part}} becomes jane

Example signature that renders differently for each mailbox:

<div>Best,</div>
<div>{{first_name}} {{last_name}}</div>
<div>{{email}}</div>

If a placeholder has no value (e.g. {{first_name}} on a mailbox without a name set), the actor warns at the end of the run and lists affected mailboxes so you can fix them.

Output

One dataset row per matched mailbox. The status field is one of:

• updated, mailbox was updated successfully. The only billable status.
• dry_run, preview only, no write happened
• skipped, no changes were needed or no fields were provided
• error, update failed, see the error field for the cause
• aborted, run was stopped before reaching this mailbox
• charge_failed_aborted, run stopped after a charge failure on a previous mailbox
• awaiting_configuration, run had no auth provided

Example row:

{
  "email": "jane@acme.com",
  "status": "updated",
  "fields_updated": ["signature", "daily_limit"],
  "chargedCount": 1,
  "updatedAt": "2026-05-15T11:30:00.000Z"
}

Pricing

$0.20 per mailbox successfully updated. Dry runs, skips, errors, aborted, and awaiting_configuration are all free. Re-runs of mailboxes that already match the desired values are also free.

FAQ

Can I re-run safely? Yes. The actor reads the current state of every mailbox and skips ones that already match what you want, so re-running with the same input costs nothing extra.

What if my run aborts halfway? Re-run with the same input. Mailboxes that were updated successfully are now in the desired state, so they get skipped on the next run.

Why didn't my mailbox change in the Instantly UI? Instantly's UI sometimes caches mailbox state. Hard-refresh the page. The dataset row shows what we sent and when.

How long do cookies last? Roughly a week. Re-export from Cookie-Editor if you see HTTP 401 in the error column.

Does this work with Instantly SSO or 2FA accounts? Use the cookies path. The email/password fallback does not handle SSO or 2FA.