Fardeen Karim
Email warm-up explained: how long it takes and what it does
What warm-up does, how long a new mailbox needs before campaigns, how fast to ramp up, and the signs that warm-up is working or not.
Fardeen KarimRead "How many emails can I send a day?" is the question I hear most. The honest answer is: far fewer per mailbox than the provider allows, and as many in total as you have mailboxes for.
The provider limit is not your target
Google Workspace lets a mailbox send up to 2,000 emails a day. That limit exists for normal business email, where most messages go to people who know you. Cold email is different: most recipients have never heard of you, fewer open, fewer reply, and some report you. Filters judge a mailbox on those reactions, and a mailbox sending hundreds of cold emails a day collects bad signals much faster than good ones.
About 30 a day per mailbox
Around 30 cold emails a day per mailbox is the number I use and recommend. It's low enough that each mailbox looks like a busy person, and high enough that a handful of mailboxes covers a serious campaign. Some senders push to 50; the risk grows faster than the volume does.
Warm-up emails come on top. While campaigns run, a mailbox might send 10 warm-up emails and 30 campaign emails a day.
Scale with mailboxes, not volume
To send more, add mailboxes and domains instead of raising the daily number:
- 30 emails × 10 mailboxes = 300 a day, about 6,000 a month on working days.
- 30 emails × 30 mailboxes = 900 a day, about 18,000 a month.
Keep three mailboxes per domain. If one domain runs into trouble, only three mailboxes are affected, and the rest of your sending carries on. Our mailbox calculator works out the numbers from the people you want to reach.
Ramp up, never jump
Volume changes matter as much as volume. A mailbox that sent 5 emails yesterday and 50 today looks suspicious even if 50 would be fine after a month. Build new mailboxes up over about three weeks: two of warm-up, one of rising campaign volume.
Spread sending through the day
Thirty emails sent in one minute looks like a blast. The same thirty spread through a three-hour window, a few minutes apart, look like someone working through their inbox. Good sending tools do the spreading for you; check that yours does. The send time planner shows which hours land in your prospects' working morning.
Watch the numbers that matter
Two numbers tell you when to slow down:
- Bounce rate: keep it under 2%. Above that, stop and clean the list.
- Spam complaints: Gmail's line is 0.3%, and you want to stay well under 0.1%. Making it easy to opt out keeps people from pressing "report spam".
If either climbs, lower the volume on that mailbox or domain before doing anything else.
The short version
About 30 cold emails a day per mailbox, three mailboxes per domain, three weeks to reach full volume, emails spread through the day, and more mailboxes when you need more volume.
mailzy campaigns have a daily limit per mailbox, spread sending through your schedule, and pause a campaign by themselves if its bounces climb too high. See campaigns.