Deliverability
Most cold email tools compete on how fast they can empty your list. ColdMerge does not. The mailbox you send from is your real work mailbox, on your real domain, and Google can take it away. So ColdMerge is built to send less than you could, more slowly than you could, and to stop when the numbers say the list is bad.
That is the whole philosophy on one line. The rest of this section explains the machinery behind it.
Your mailbox is the asset, not the campaign
Section titled “Your mailbox is the asset, not the campaign”ColdMerge sends through your own Gmail or Google Workspace account. There is no
shared sending service in the middle, no pool of rented servers, no other
customers whose behaviour affects yours. Your address is the From:, replies
land in your own inbox, and every message counts against your own Google quota.
That is the good part. It also means the downside is yours. If Google decides your account is sending spam, it does not throttle a server somewhere. It suspends the account you read your mail in.
Think of it like driving your own car to work rather than taking a company van. Nobody else can dent it. But nobody else pays for the repairs either.
Every limit described in this section exists because of that one fact.
Two stances that shape everything
Section titled “Two stances that shape everything”ColdMerge holds two positions that sound contradictory until you see where the line sits.
Warn, never block. For anything where you might reasonably know better than the software, ColdMerge tells you and gets out of the way. A weak SPF record, a missing DMARC policy, an elevated bounce rate, a list full of risky addresses: all of these produce a clear warning and then let you decide. You are the operator. The software is not your supervisor.
There is exactly one hard block at setup, and it is the one case where the software is certain and you are not: if a probe send proves your DKIM signature does not line up with your sending domain, a campaign cannot launch until that is fixed. Read more in Mailboxes and sending domains.
Nudge, never gate. Email verification is advice, not a verdict. If ColdMerge checks an address and the provider says it is dead, that address is skipped by default at launch and you can include it anyway with one click. A dead result never adds anyone to your suppression list, and never marks a contact undeliverable. Only a real bounce or a real unsubscribe does that, because those are facts and a verification guess is not. See How ColdMerge sends.
The one exception to both stances is the bounce circuit breaker, which does stop a campaign on its own. It is the seatbelt, and it exists because the thing it prevents (losing your Google account) cannot be undone.
Where to go next
Section titled “Where to go next”Ramp-up and send budgets Why a new mailbox only sends 20 emails on its first day, how the allowance grows over about five weeks, the four separate limits that can hold a mailbox back, and what “Stopped: this mailbox has used all of its sends” really means.
Pacing and sending windows Why your emails trickle out with random gaps instead of going in one burst, why there is a working-hours window at all, and what happens to the unsent remainder when the window closes for the day.
Bounces and the circuit breaker What a bounce rate is telling you, the exact rule that auto-pauses a campaign, why the pause does not lift itself, and why resuming without cleaning the list is the most dangerous button in the product.
How ColdMerge sends The honest-sender position in full: rotation across mailboxes, suppression that nothing can bypass, real unsubscribe links that keep working for years, and why there is no warmup pool and never will be.