Overview
Connect the mailbox your outreach is sent from. Emails go out through your real mailbox, so they look and thread like anything else you send, and replies come back to you. What is sent — who gets contacted, what each email says, how many days apart — is set up in Dashboard → Autopilot. A connected mailbox on its own never sends anything.Setup
Go to Integrations → Email and click Add another mailbox (or connect your first one). The page shows how many mailboxes your plan allows — N of M mailboxes.Option A — Gmail or Google Workspace (recommended)
Click Connect Gmail and approve access. Sending happens through your real Gmail account: no DNS to set up, best deliverability, native threading.Option B — Outlook or Microsoft 365 (recommended)
Click Connect Outlook and approve access. Same as above, through Microsoft.Option C — Your own domain
For a sending address on a domain you own that is not on Google or Microsoft. Click Set up a custom-domain address, enter the from name and address, then add the DNS records shown to your domain and click Check verification. DNS changes usually take a few minutes.Personal mailbox domains (gmail.com, outlook.com, yahoo.com…) are rejected on
this path — use the Gmail or Outlook buttons instead.
Finish: your sender identity
Commercial email has to say who is sending it. Under Settings → Outreach → Email signature set your name, your company and a postal address, and optionally your photo or logo, phone and website. Every outreach email also carries a standard unsubscribe header, which mail clients turn into their own one-click unsubscribe button. You can add a visible opt-out as well: a P.S. in your own words (“just tell me and I’ll stop”) or a plain unsubscribe link. An unsubscribe stops every channel for that person, not just email.Mailbox settings
Open a mailbox row to see its settings.Warm-up
A newly connected mailbox starts at 5 emails on its first day and climbs by 5 a day until it reaches the daily limit you set. A brand-new address has no reputation to spend, and providers score the pattern: fifty cold emails on day one reads as a list. The row shows5/day · warming up while this is happening, and how many days are
left until the full limit.
You can switch warm-up off if the address genuinely is not new to sending — an
established domain, or a mailbox reconnected after being removed. CallPrep will
warn you first and record the decision, because the cost of getting it wrong is
the reputation of the address itself, not just one campaign.
How sending works
- One mailbox per lead. A lead is assigned a mailbox when it enters a sequence and keeps it, so the whole conversation comes from one address.
- Follow-ups thread. Later emails reply inside the first email’s thread, with
a
Re:subject, so the lead sees one conversation rather than five cold emails. This is a per-Autopilot setting. - First emails come first. When there is more to send than the daily limit allows, leads who have never been contacted are served before follow-ups — the capacity bar on the Autopilot page shows the split, and Upcoming sends shows the queue behind it.
- One email per lead per day, regardless of how many steps come due.
- Several mailboxes share the load. New leads are assigned to whichever mailbox has the most room, counting warm-up, pause state and role.
Replies and bounces
Replies. For Gmail and Outlook mailboxes, CallPrep notices a reply and stops the sequence (if the Autopilot has stop on reply on, which is the default). Out-of-office and auto-replies do not count as an answer. A reply logged on the HubSpot contact also stops the sequence, which is the safety net for custom-domain mailboxes. Bounces. A permanent bounce stops the email steps for that lead — other channels continue, since it is the address that failed, not the person. If more than 5% of a mailbox’s emails bounce permanently over a week (measured once it has sent at least 20), the mailbox is paused automatically and you get an email explaining why. Temporary delays do not count.What CallPrep can read
The reading is used for one purpose: noticing that a lead answered, and that a
message bounced. Only addresses that belong to a lead in a live sequence are
matched — anything else is passed over and nothing about it is stored.
When a mailbox stops working
OAuth access can end without warning — a password change, a revoked grant, an admin policy. When that happens the mailbox is marked Disconnected, the dashboard shows a red banner, and you get an email asking you to reconnect. The other mailboxes keep sending in the meantime, at reduced capacity. A send that failed because the authorization was dead is retried after you reconnect — those leads are not skipped. If a send fails for another reason, the mailbox row explains it in plain language (a Google account without Gmail enabled, a domain not verified yet, rate limiting), with the provider’s own wording under Technical details.Credits
Researching a lead costs one credit. Sending emails is free, and so is a skipped or rescheduled email. See Credits.Frequently asked questions
Can CallPrep read my emails?
Can CallPrep read my emails?
On Gmail it can read headers only — who a message is from, to, its subject
and date — never the body. On Outlook it can read everything except the body,
attachments and previews. With a custom-domain sender it has no read access at
all. It uses this to spot replies and bounces for leads in a live sequence.
How many mailboxes can I connect?
How many mailboxes can I connect?
It depends on your plan — the top of the Email page shows N of M mailboxes
and hides the add button once you are at the limit. Reconnecting an address you
already have never counts as a new mailbox, so you can always repair what you
have. See the Billing page.
Why is my new mailbox only sending 5 emails a day?
Why is my new mailbox only sending 5 emails a day?
That is the warm-up ramp: 5 on day one, +5 each day until it reaches your daily
limit. The row shows how many days are left. It can be switched off, but only
do that if the address has an established sending history.
Why are my emails on hold?
Why are my emails on hold?
Your sender identity is incomplete. Commercial email must identify the sender,
so email steps wait until your name, company and postal address are filled in
under Settings → Outreach → Email signature. Other channels keep running.
Do follow-ups look like a new cold email each time?
Do follow-ups look like a new cold email each time?
No. Follow-ups are sent as replies in the first email’s thread, keeping one
subject and one conversation. You can turn threading off per Autopilot.
Someone answered — will they still get the next email?
Someone answered — will they still get the next email?
Not on Gmail or Outlook: the reply is detected and the sequence stops, and the
check is repeated right before each send. With a custom-domain mailbox CallPrep
cannot see the reply — log the email on the HubSpot contact, or close the lead
from the Autopilot’s Activity view.
My mailbox was paused automatically. What happened?
My mailbox was paused automatically. What happened?
More than 5% of its emails bounced permanently over the last week (counted once
it has sent at least 20). That is a deliverability alarm, not a quota — check
where the addresses came from before resuming. You will have had an email
explaining it.
Which address do replies come back to?
Which address do replies come back to?
The mailbox marked Collect replies here. If a lead’s sequence is sent from a
different mailbox, that address is used as the reply-to, so the conversation
lands in one place.
Can I use one mailbox for imports and another for inbound leads?
Can I use one mailbox for imports and another for inbound leads?
Yes — that is what This mailbox sends is for. Set one to Imported leads
only and another to Organic leads only, and bulk-list risk stays off the
address you actually converse from.
What happens to unsubscribes?
What happens to unsubscribes?
The person is added to your suppression list and every active sequence for them
stops — on all channels, not just email. Suppression is permanent and is never
cleared by a re-import.