Cold email deliverability without risking your domain

1. Never send cold email from your main domain

Your company domain carries your invoices, your team's email and your customers' trust. If a cold campaign earns spam complaints or bounces, that reputation can suffer. So we never send from it. Every campaign goes out from separate sending domains that look like yours, registered for outbound only, each with its own inboxes.

How SLSBMB does it: every sending domain carries four inboxes; the $800 Sending Engine entry is two domains and eight inboxes.

2. Authenticate every domain

Receiving mail servers check whether a domain says who may send for it and whether messages are signed.

• SPF lists the servers allowed to send for the domain.
• DKIM signs each message so it can't be altered in transit.
• DMARC tells receivers what to do with mail that fails those checks.

How SLSBMB does it: SPF, DKIM and DMARC are set up for every sending domain before warmup starts.

3. Warm new inboxes before the first cold email

A brand-new inbox that suddenly sends hundreds of emails looks like a spammer. Warmup builds a normal history first: a gradually growing volume of ordinary business correspondence between inboxes, which is delivered, opened and answered.

How SLSBMB does it: every inbox warms for about 21 days from the moment it exists. The first campaign emails go out around day 22, and only once the complete set of inboxes is connected and stable and every launch check is clear. Warmup keeps running alongside the campaigns.

4. Keep daily volume per inbox low, and spread it out

Volume concentrated in a burst looks automated. Volume spread across the working day at a modest rate looks like a person.

How SLSBMB does it: at most 15 campaign emails per inbox per sending day, spread through the sending window instead of sent in bursts. More volume comes from more domains and inboxes — that is what a larger Sending Engine budget buys — never from pushing each inbox harder.

5. Email verified business addresses only

Bounces are one of the strongest negative signals a sender can produce.

How SLSBMB does it: contacts count only once their business email is verified as deliverable. We never email private inboxes.

6. Write plain text, like a person

How SLSBMB does it: campaigns are plain-text sequences — no tracking pixels or heavy formatting — with the sender's physical address and an opt-out line.

7. Make it easy to say no, and respect it forever

How SLSBMB does it:

• Every email carries a one-click unsubscribe link on the sending domain.
• Anyone who unsubscribes, complains, bounces or asks not to be contacted is blocked for good.
• An ordinary reply — even "not now" — stops that person's follow-ups at once.

8. Read every reply

Auto-replies, bounces and unsubscribes must be handled quickly, and interested people must not wait.

How SLSBMB does it: every reply is read and sorted. Junk and automatic replies are filtered out, and the people who want to talk land in your SLSBMB AI inbox and CRM.

What no one can promise

Deliverability depends on recipients' mail systems, which change their rules without notice. We can run the infrastructure carefully; we can't guarantee inbox placement, and nobody honestly can.

Frequently asked questions

Why do the first cold emails go out on day 22?

New inboxes need about three weeks of warmup before cold email lands in the inbox instead of spam. We warm yours for 21 days, so the first campaign emails go out around day 22.

How many cold emails can one inbox send a day?

We send at most 15 campaign emails per inbox per sending day. To send more, add domains and inboxes instead of pushing each inbox harder.

Will cold email hurt my company domain?

Not if you never send it from your company domain. SLSBMB sends only from separate, authenticated and warmed sending domains.

Do I need SPF, DKIM and DMARC for cold email?

Yes. All three should be set up on every sending domain before you send. SLSBMB configures them for every domain it registers.