Skip to main content

Mailboxes

A mailbox is a sending account — the real email address your campaigns send from, along with its credentials, signature, BCC, and sending pace. Mailboxes are independent of brands: a brand is your business identity, a mailbox is where mail goes out from. Every campaign is assigned one brand and one mailbox at creation, and any brand can be used with any mailbox.

You can connect as many mailboxes as you need — your plan limits brands, not mailboxes.

Adding a mailbox​

Adding a mailbox walks you through four steps.

1. Connect your mailbox​

  • Email Provider — choose Gmail, Outlook, Yahoo, or Custom (to enter your own SMTP/IMAP settings directly).

  • Email Address (required for Yahoo and Custom) — the address this mailbox will send from. Gmail and Outlook don't ask for it: the account you sign in with supplies the address, so the field isn't shown.

    Deliverability best practice

    Use a dedicated secondary email or domain for outbound outreach (e.g. you@getcompany.com) rather than your primary address (you@company.com), to protect your main domain's sender reputation.

Gmail and Outlook connect by signing in. Instead of the credential fields, this step shows a single Sign in with Google or Sign in with Microsoft button. Clicking it opens your provider's sign-in window; finish there and the wizard picks it up automatically, then completes with Finish Creating Mailbox — the password step never appears. If your browser blocks the popup, use the Open the sign-in page link Aimly shows while it waits. Next does nothing for these two, because signing in is the only way forward.

If you'd rather drive a Gmail or Outlook mailbox over SMTP/IMAP with an app password, pick Custom and enter the host settings yourself. For provider-specific setup steps — like generating an app password for Gmail — see Integrations.

2. Secure your mailbox​

Only Yahoo and Custom mailboxes reach this step. Enter the mailbox's password or app password.

Your credentials are verified live against a real SMTP and IMAP connection before the mailbox is saved — if either check fails, you'll see the specific error rather than a generic failure.

3. Signature and BCC​

Optional, but recommended for a polished sender identity:

  • Email Signature — appended to every email sent from this mailbox.
  • BCC Address (optional) — automatically blind-copied on every email this mailbox sends, useful for keeping a record in another inbox.

4. Rate limiting​

Controls how fast this mailbox sends, to protect its sender reputation. Leave this on the default unless you specifically understand the deliverability trade-off:

  • Automatic (Adaptive) (recommended) — safely scales your daily sending volume based on this mailbox's health, starting conservatively and increasing as your sending history builds up.
  • Fixed Daily Limit — caps sending to a fixed number that never increases, regardless of mailbox health.
  • Skip rate limiting — emails send immediately with no pacing gap at all. This bypasses the protection rate limiting is built for — only use it if you understand the risk to your sender reputation.

Things worth knowing​

  • A mailbox's address and server settings can't change. The email address, hosts, ports, and Sent folder are locked once the mailbox is saved. You can still update the password (or re-sign in), signature, BCC, and rate limiting. To use a different address, add a new mailbox.
  • A campaign's mailbox can't change. Once a campaign is created with a mailbox, that link is permanent — to switch, create a new campaign with the right mailbox.
  • Deleting a mailbox deletes every campaign using it. This includes each campaign's emails, templates, and automations — not just the mailbox itself. Aimly lists the affected campaigns before you confirm. Deleting a mailbox also frees its plan slot and its address for reuse.
  • Failure alerts are per mailbox. If a mailbox fails three emails in a row, Aimly emails you an alert naming it, at most once every six hours per mailbox.
  • Sending starts immediately after setup, using a conservative default pace. Aimly refines your safe sending volume automatically over time based on your mailbox's actual sending history.