Sequences that optimize while you sleep
Sendbox campaigns let you stack email steps with custom wait windows, run several A/B variants side by side, branch logic with IF/THEN/ELSE rules, and rotate phrasing through spintax. The optimization engine watches performance and quietly benches the variants that underperform. Because each mailbox is permanently tied to its own dedicated IP through sticky hash assignment, none of that sending shares infrastructure with anyone else.
Campaigns
Outreach
Draft the sequence
Stack email steps and set wait periods measured in hours or days. Write A/B variants per step (A, B, C, and beyond), branch the copy with IF/THEN/ELSE conditions tied to any variable, and rotate phrasing using spintax like {option1|option2|option3}, nesting included.
- Branching logic per step
- Fatigue detection on your copy
- Event webhooks
- Granular stop-on-reply rules
A look inside the Sendbox dashboard, where Campaigns lives.
Campaigns
Campaign | Status | Leads | Sent | Opened | Replied | Positive | Bounced | |
|---|---|---|---|---|---|---|---|---|
Fintech Ops Leaders | Active | 3,600 | 2,510 | 1,620(64.5%) | 189(7.5%) | 79(41.8%) | 41(1.6%) | |
Seed Stage Founders – NYC | Active | 1,500 | 980 | 615(62.8%) | 112(11.4%) | 54(48.2%) | 14(1.4%) | |
Agency Growth Partners | Paused | 4,800 | 3,204 | 1,798(56.1%) | 176(5.5%) | 61(34.7%) | 71(2.2%) | |
Enterprise Security Buyers | Completed | 6,300 | 4,488 | 2,915(64.9%) | 402(9.0%) | 161(40.0%) | 79(1.8%) | |
Ops Leaders Q2 2026 | Draft | 760 | - | - | - | - | - |
Set it up once, let it run
Branching logic per step
IF/THEN/ELSE conditions keyed to any variable, so different leads see different messaging depending on their data.
Fatigue detection on your copy
Sendbox flags copy that's gone stale and can regenerate or pause that variant automatically.
Event webhooks
Fire off webhooks for lead.created, lead.replied, email.sent, email.opened, and lead.bounced, configured per campaign.
Granular stop-on-reply rules
Stop on any reply, stop only on auto-replies, or stop the moment anyone at that company responds, plus CC/BCC and unsubscribe-link controls.
Step 1
Draft the sequence
Stack email steps and set wait periods measured in hours or days. Write A/B variants per step (A, B, C, and beyond), branch the copy with IF/THEN/ELSE conditions tied to any variable, and rotate phrasing using spintax like {option1|option2|option3}, nesting included.
Step 2
Assign senders and leads
Choose which mailboxes carry the sequence. Sendbox spreads the load with round-robin, random, or priority rotation, and automatically works out each lead's timezone from their city or country if that data was imported.
Step 3
Ship it and let optimization run
Define a sending window with start and end times, pick your working days, and skip holidays automatically. The optimization engine benches underperforming A/B variants on its own. A reply from any lead halts their sequence the instant it lands.
Where it fits
Agency outreach across clients
Run every client's campaigns on infrastructure that's entirely their own. Each mailbox maps to a single IP by MD5 hash permanently, so nobody shares sending reputation with anyone else on the platform.
Scaling an SDR team
Spread sends across dozens of connected mailboxes using round-robin, random, or priority rotation. Cap each campaign's sending window so no single mailbox exceeds its daily volume.
Personalization at volume
Drop in variables like {{firstName}} and {{company}}, plus any custom field you've defined. Layer conditional logic on top so different segments of your list see genuinely different copy.
Every send traced back to your own IP
Your own IP, never someone else's mess
Plenty of cold email platforms pool every customer onto the same sending servers, so a stranger's spam complaint tanks your inbox placement too. Sendbox pairs every mailbox to its own dedicated IP through sticky hash mapping, permanent, not reshuffled. Whatever reputation you build stays yours alone.
- Beats Instantly
- Beats Smartlead
- Beats Lemlist
Sending windows that respect the lead's clock
Sendbox works out each lead's timezone from the country or city on file, then sends only inside the window you configure, with a start time, an end time, chosen working days, and holidays skipped automatically.
- Your prospect sees the email land during their workday, not yours.
Optimization does the picking for you
Skip babysitting your A/B tests.
- The optimization engine reallocates volume toward whichever variant is winning and pauses the ones that aren't, based on thresholds you set: minimum sends per variant, minimum days before it acts, and an auto-pause trigger.
There's no hard cap, add as many steps as the campaign calls for, each with its own wait period in hours or days. Most sequences that convert well land somewhere between 4 and 7 steps.
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.
