Why warm-up is needed
Gmail and Outlook judge a sender by its history. A mailbox with no history that suddenly sends hundreds of emails looks like a spammer, and its emails end up in the spam folder.
A sample warm-up schedule
| Period | Daily emails (per mailbox) | Note |
|---|---|---|
| Day 1 | 10 | Carry on with normal business email alongside |
| Days 2–9 | +5 a day | Keep an eye on bounces and complaints |
| After that | 50 at most | Add mailboxes rather than pushing volume |
These are Repmight's default limits, with random gaps of 3–15 minutes and sending on weekdays in working hours only.
About warm-up networks
Some tools offer networks where mailboxes email each other and mark the messages as important. Opinion is split on these: providers can spot artificial engagement, and it's no substitute for how real recipients behave. The most reliable warm-up is real email, in small numbers, that people reply to.
Signs to watch
- Bounce rate above 2–3%: clean your list
- Spam complaints nearing the 0.3% limit Gmail states: stop sending
- Few replies: fix your targeting and wording, don't send more
Before you start
- Set up SPF, DKIM and DMARC
- Send under a real person's name, with a real signature
- Use a system that suppresses bounces and opt-outs automatically
FAQ
How long does email warm-up take?
Usually 2–4 weeks. How long matters less than building up slowly and keeping bounces and complaints low.
Do I need to warm up my existing business address?
If you already use it for everyday email, it has a reputation. Even so, building up cold outreach gradually is the safest approach.