Warmup runs on a strategy (a named preset of ramp-up parameters) plus a set of individual settings that fine-tune behavior on top of the strategy. Most users never need to leave the Standard preset. If you do, every parameter is exposed.
This guide covers both layers: pick a strategy, then optionally tune individual settings.
New domain (less than 6 months old)? -> Standard
Domain you bought or inherited? -> Standard
Domain has been blacklisted in the past? -> Standard
Established domain (6+ months) with clean sending history? -> Aggressive may be appropriate
Need very specific volume parameters? -> Custom
Not sure? -> Standard. You can switch later without resetting your day counter.
The safest and most widely used preset. Right for most accounts.
Parameter | Value |
|---|---|
Starting volume | 5 emails/day |
Daily increase | +1 email/day |
Maximum | 20 emails/day |
Time to full ramp | ~14 days |
When to use:
New domains (under 6 months)
New accounts with no prior sending history
First-time warmup users
Any account where domain reputation is uncertain
Why it works: ISPs are forgiving of very gradual volume increases. Starting at 5/day and adding 1/day creates a smooth ramp that rarely trips spam filters. By Day 14 you're at ~18/day, hitting the 20/day ceiling around Day 16 with two weeks of consistent positive engagement on record.
Faster ramp-up, higher ceiling. Suitable for accounts with existing reputation.
Parameter | Value |
|---|---|
Starting volume | 7 emails/day |
Daily increase | +2 emails/day |
Maximum | 28 emails/day |
Time to full ramp | ~14 days |
When to use:
Established domains (6+ months) with clean sending history
Domains being re-warmed after a pause
Campaigns will send "on-the-limit of allowed" volume
Mailboxes on Google Workspace / Microsoft 365 with prior good infrastructure
When NOT to use:
Brand new domains - the faster ramp can trip filters before you build any reputation
Domains with unknown history (purchased, inherited)
Accounts that have been blacklisted
Risk: Aggressive carries more downside than Standard. The faster volume jumps give ISPs less time to build confidence between increases. If your domain doesn't already have trust signals, this can backfire and undermine warmup.
Full manual control. For advanced users with specific volume requirements.
Parameter | Value |
|---|---|
Starting volume | Fixed at 5 (Standard's |
Increase per day | You set it (1-10) |
Maximum | You set it via Warmup Daily Limit (0-30) |
Time to full ramp | Depends on your inputs |
When to use:
You have specific daily-volume targets driven by your sending plan
You're managing multiple accounts that need different ramps
You want to be MORE conservative than Standard (e.g., start at 2/day, +1 every 2 days)
Tips:
Start low. Even on Custom, opening with under 5/day is the safer default for any new account.
Keep daily increases small. 1-2/day is safe; 5+/day is aggressive territory.
Set a realistic maximum. Match your long-term sending volume (warmup + campaigns combined).
Monitor closely. Custom has no guardrails - you own the outcome.
In addition to the three strategies, warmup has a Ramp-Up toggle:
Ramp-Up on (default): volume increases progressively each day. Recommended for all new warmup setups.
Ramp-Up off (Flat mode): same fixed volume every day from Day 1. No gradual increase.
Use Flat mode only for accounts that already have established reputation and need maintenance-level warmup. Turning Flat on for a new account at high volume is essentially skipping warmup. Expect spam.
These tune behavior on top of whichever strategy you picked. All are exposed on the Warmup tab of any account in Email Accounts, and via Bulk Edit Settings for multiple accounts at once.
Important - preset vs Custom semantics: Warmup Daily Limit, Increase per day, and Warmup Randomizer ONLY apply when the strategy is Custom. On Standard and Aggressive, the preset's curve is used as-is and these three sliders are ignored. The remaining settings (Reply Rate, Skip Weekends, Business Hours Timezone, Automation Language) apply on every strategy.
Range: 0-30. Default: 15. Custom only.
The ceiling for daily warmup volume on Custom strategy. The Custom curve grows from 5 emails/day (a fixed safe baseline) by your Increase per day setting until it reaches this limit, then stays flat.
Used in two more places regardless of strategy:
Flat mode (Ramp-Up turned off) sends exactly this volume every day from Day 1.
After the 14-day ramp completes (badge shows Active), the system targets a maintenance-level volume that respects this number when calculating its rolling-average baseline.
Don't confuse this with Max Emails Per Day (also called Messages Per Day) on the same account - that's the account-wide daily cap covering campaigns + warmup combined, set separately on the campaign settings card. Account-wide default is 30.
Range: 1-10. Default: 1 (Standard) / 2 (Aggressive). Custom only.
How many emails are added to the daily target each day during the Day 1-14 ramp. This is what differentiates Standard (+1/day) from Aggressive (+2/day). On Custom strategy you set it directly. On presets it's locked - changing the slider has no effect; the preset's value is always used.
Range: 0-50%. Default: 0%. Custom only.
Each warmup email has this probability of being skipped, creating natural day-to-day variation. The slider description in the UI confirms this: "Each email has this chance to be skipped for natural variation". It's a negative offset only - it can reduce daily volume but never push above the target.
Example. Today's target is 15 emails, randomizer is 30%:
~70% of those 15 actually get sent -> ~10-11 emails
The remaining ~30% are skipped this day
0% (default) means no skipping. Every email in the daily plan ships.
20-35% is a reasonable range if you want some variation. ISPs notice perfectly consistent daily volumes, so a small randomizer can help.
50% is the maximum and creates wide day-to-day swings. Use only if you specifically want high variance.
This setting does not appear in Bulk Edit Settings - it's only configurable in single-account mode.
Default: off.
When enabled, no warmup emails are sent Saturday or Sunday.
When to enable:
B2B sending domains where weekend mail looks unnatural
Accounts that should match a specific business persona
Industries with strong weekday-only norms (legal, enterprise)
When to leave off:
B2C or mixed-use domains
Accounts in early warmup - skipping weekends costs you 2 reputation-building days/week
When speed matters - weekday-only warmup takes longer to build the same reputation
Calendar impact: with Skip Weekends ON, the "14-day warmup" refers to 14 sending days, not calendar days. Real elapsed time is ~19-20 calendar days.
UI range: 20-80%. Stored default: 35%. Preset reply rates: Standard = 30%, Aggressive = 40%.
Base probability that each warmup email triggers a reply chain from the receiving seed. At 50%, roughly half of warmup emails get replies. Reply chains can go up to 3 levels deep (your email -> seed reply -> your reply -> seed reply), with each subsequent reply slightly less likely than the previous one.
Higher end (60-80%):
More reply conversations = stronger engagement signals
Each reply adds open + send events to your reputation
Multi-turn threads look highly natural to ISPs
Trade-off: uses more daily quota on reply-related sends
Lower end (20-40%):
More daily volume goes to new conversations (broader reach across the seed pool)
Fewer deep threads, more breadth
Appropriate for accounts focused on volume over depth
The slider is hard-capped at 20% on the low end and 80% on the high end - there's no "0% replies" or "100% replies" option. If your inbox rate is low, bumping the reply rate up is one of the easiest fixes; replies are the strongest positive signal warmup generates.
Default: English.
Language that is used to generate warmup email content. Supports English, French, German, Spanish, Portuguese, Italian, Russian, and more.
Why language matters: ISPs profile your account from the content you send and from how recipients react to it. The domain TLD is a weak signal at best - cold senders routinely use generic .com / .io / .co domains to reach any market in the world. What matters is internal consistency: does your warmup language match what your campaigns are doing, and does that match the audience you're actually targeting?
Match the language to the audience your campaigns will target. Selling into the French market? Warm up in French. Selling into the LATAM Spanish-speaking market? Warm up in Spanish. The domain itself is irrelevant - your acme.com mailbox can warm up in any language.
Match the language to the offer. A German B2B SaaS pitched to German buyers should warm up in German, even if the sending domain is a generic .io. The audience and the offer drive the choice, not the registrar.
If you target multiple markets with separate campaigns, run separate accounts per market and pick each account's warmup language to match its specific audience. Don't pick "the primary one" and hope the rest catches up.
Default: organization timezone, falls back to UTC.
Determines the business-hours window for warmup sending. Emails are planned only during business hours (~9 AM to 5 PM) in this timezone. Day boundaries for warmup analytics are also based on it.
Match this to your actual sending region. If you're in New York, use America/New_York.
Don't leave it as UTC unless you actually operate in UTC. Warmup emails arriving at 3 AM local time look suspicious.
If you manage accounts across multiple regions, set each account's timezone individually.
Setting | Speeds Up Ramp | Improves Safety | Notes |
|---|---|---|---|
Higher Warmup Daily Limit | Yes | No | Raises Custom strategy's ceiling |
Higher Randomizer | No | Yes | More natural daily variation |
Skip Weekends ON | No | Yes | Natural for B2B but extends real warmup duration |
Higher Reply Rate | Neutral | Yes | Stronger signals, uses more daily quota |
Correct Language | No | Yes | Aligns warmup with the language of the audience your campaigns target |
Correct Timezone | No | Yes | Business-hours sending looks natural |
You can change strategy or any individual setting at any time without pausing warmup:
Go to Email Accounts, click an account, open the Warmup tab.
Change the strategy or sliders.
Changes take effect once saved.
When you change strategy, warmup continues from the current day - it doesn't reset to Day 1. If you switch from Standard to Aggressive on Day 8, the system computes Day 8's volume using the Aggressive formula.
For multiple accounts at once, use Bulk Edit Settings from the Email Accounts table - the same panel opens for all selected rows.
What to Expect from Warmup - the visible Day-counter ramp and the Active steady state.
Warmup and Campaign Sending Together - how the daily limit is shared once campaigns start sending.
