Connect every mailbox you need. Warmup handles itself.
Add Gmail, Outlook, or any provider that speaks IMAP/SMTP. Once connected, warmup kicks off in the background on its own — you set the volume targets and reply-rate goals, Sendbox does the rest. DNS health checks continuously confirm your SPF, DKIM, and DMARC records are configured correctly.
Lambda Group
Mailboxes
Email | Status | Sent / Limit | Tags | Warmup Stats | Warmup | Sending | |
|---|---|---|---|---|---|---|---|
alex@yourcompany.com Alex Johnson | Active | 14/50 | Cold Outreach | Day 2122/2591% health | |||
sarah@yourcompany.com Sarah Mitchell | Active | 31/50 | Cold Outreach | Day 1819/2587% health | |||
outreach@senddomain.io Outreach Pool | Active | 5/25 | Warming Pool | Day 78/2574% health | |||
alex@seconddomain.io Alex (Domain B) | Active | 28/50 | Cold Outreach | Day 1617/2583% health | |||
sales@cold-mailer.com Sales Team | Active | 42/50 | Agency | Day 2424/2594% health | |||
jenny@thirddomain.io Jenny Lee | Active | 19/50 | Cold Outreach | Day 1213/2579% health | |||
tom@outbound.agency Tom Rivera | Active | 37/50 | Agency | Day 2021/2588% health | |||
priya@yourcompany.com Priya Sharma | Active | 8/25 | Warming Pool | Day 56/2568% health |
One connection, indefinite sending
Connect as many mailboxes as you like — Gmail OAuth, Outlook OAuth, or custom IMAP/SMTP — with nothing charged per seat.
Background workers operate continuously against the starting volume, daily ramp, target, and reply-rate goals you configure.
Every connected mailbox gets its SPF, DKIM, and DMARC records validated, so configuration problems surface before they hurt sending.
Each mailbox reports its current state — active, inactive, error, warming_up, suspended, or failed — so you always know where things stand.
Get a new mailbox sending in under sixty seconds
Add Gmail or Outlook through OAuth in a couple clicks, or hook up any other provider with IMAP/SMTP credentials. Google and Microsoft users skip the app-password hassle entirely.
Background workers cycle every 5 to 30 seconds. Set your starting volume, how fast it should ramp, the target volume, and your reply-rate goals — then step back. Warmup just happens.
Choose which mailboxes send for each campaign and pick a rotation mode — round-robin, random, or priority. Sendbox honors each account's daily limit and matches ESPs where it can.
Connect as many mailboxes as your client roster needs, across as many domains as you want. Rotation spreads the load so no single account carries too much.
Define your starting volume, daily ramp, and target, then let the warmup workers take it from there while you build out campaigns in the background.
Mix Gmail and Outlook mailboxes inside a single campaign. ESP matching sends Gmail leads through Gmail senders and Outlook leads through Outlook senders automatically.
Every mailbox gets its own dedicated IP
Warmup you don't have to babysit. DNS checks that catch mistakes early.
Warmup shouldn't be a switch you flip and hope for the best. Sendbox's background workers cycle every 5 to 30 seconds against volume and reply-rate targets you configure. DNS validation continuously checks your SPF, DKIM, and DMARC records, so misconfigurations get caught before they cost you deliverability.
Warmup with real dials to turn
Set your starting volume, how fast it ramps daily, the target volume, and your reply-rate goals. Background workers handle execution, cycling every 5 to 30 seconds, and vary activity naturally so it doesn't read as automated to email providers.
Three ways to rotate senders
Assign several mailboxes to one campaign and choose how sends get distributed: round-robin spreads evenly, random keeps it unpredictable, priority lets you favor specific senders. ESP matching routes through the right provider whenever it can.
Got questions? We've got answers.
Still stuck? Talk to us →As many as you want — there's no cap tied to your plan. Connect five or five hundred.
Related pages
More Outreach features
Explore Sendbox
Ready to land in primary?
Get your own isolated Sendbox setup running and start sending inside 15 minutes.
Every plan includes a dedicated IP. Cancel whenever you want.