What You'll Learn
By the end of this guide, you'll understand how lemlist's sending algorithm works, why scheduling matters for deliverability, and how to optimize your campaign timing to protect your domain reputation and maximize inbox placement.
Why This Matters
Sending too many emails too quickly damages your domain reputation and triggers spam filters. Without smart scheduling:
❌ ISPs flag your domain as a spammer
❌ Emails land in spam folders
❌ Your domain gets blacklisted
❌ Reply rates plummet
lemlist's sending algorithm prevents these issues by:
✅ Spreading emails throughout the day naturally
✅ Preventing sudden volume spikes
✅ Respecting your sending limits automatically
✅ Protecting your domain reputation
What You Need Before Starting
A lemlist campaign with leads imported
A campaign schedule configured (Campaign settings → Schedules & launch)
Understanding of your daily sending limits
Knowledge of your target audience's timezone
Key Concept: Why Scheduling Matters
The Problem with Sending Too Fast
ISPs (Gmail, Outlook) monitor your sending patterns. If you send 500 emails in 10 minutes, it looks like spam. Natural human behavior means spacing emails out over hours.
What happens without proper scheduling:
ISPs detect unnatural sending patterns
Your domain reputation drops
Emails go to spam or get blocked
Bounce rates increase
What scheduling achieves:
Emails sent at consistent intervals (e.g., one every 15–20 minutes)
Natural-looking sending patterns
Better inbox placement
Protected domain reputation
How lemlist's Sending Algorithm Works
What the Algorithm Does
The lemlist algorithm automatically adjusts email delivery speed and volume based on multiple factors to protect your domain reputation.
Key factors the algorithm monitors:
1. Bounce rates If bounces increase, the algorithm slows sending to prevent further damage.
2. Open rates Low open rates signal poor deliverability—the algorithm adjusts accordingly.
3. Domain age New domains send slower initially (warm-up period).
4. Technical configurations Domains with proper SPF/DKIM authentication can send more safely.
5. Custom tracking domain quality A verified custom tracking domain improves sending capacity.
What the Algorithm Prevents
❌ Sending large volumes at once (looks like spam)
❌ Exceeding your maximum email limit (set by you or your email provider)
❌ Unnatural sending patterns (e.g., 100 emails in 5 minutes, then nothing)
❌ Overwhelming recipient inboxes (multiple emails to the same domain at once)
How Sending Speed Is Calculated
Example: If your campaign settings show "Reach a new lead every 20 minutes", this applies to the first step of your sequence.
What this means:
The algorithm spreads your first-step emails throughout your scheduled timeframe
If you have 100 leads and schedule 8 hours of sending (9 AM–5 PM), emails are spaced evenly
Follow-up steps (step 2, 3, etc.) are sent based on delays you set between steps
Daily contact capacity: The algorithm estimates how many leads will be contacted daily based on:
Your scheduled timeframe (e.g., 9 AM–5 PM = 8 hours)
Your sending limit (e.g., 50 emails per day)
The number of active leads in your campaign
Customizing Your Campaign Schedule
Set Your Sending Timeframe
By default, lemlist sends during office hours in your timezone (e.g., 9 AM–5 PM). You can customize this.
Why it matters:
Send when your audience is most active
Avoid sending at 2 AM (looks suspicious)
Match your target audience's timezone
How to customize:
From the left sidebar, click Campaigns, then open the campaign you want to edit.
Click the Settings (gear) icon, open Schedules & launch, then click the ... menu and select Modify this schedule.
Update the schedule name (optional), select the timezone, choose the sending days, set the sending window (Between/And), set how often to reach a new lead, then click Save changes.
Control Sending Speed
"Reach a new lead every" setting: This controls the interval between new leads contacted (your campaign pacing).
Example:
"Every 20 minutes" = ~3 new leads per hour
Over an 8-hour day, that's ~24 new leads
How to adjust:
Open your campaign, go to the campaign Settings (gear), then Schedules & launch, and choose Modify this schedule.
Change Reach a new lead every to a slower or faster interval, then click Save changes.
Shorter interval = faster sending (be careful!)
Longer interval = slower, safer sending
💡 Pro tip: Start with 15–20 minutes per email for new domains. Increase speed gradually as your reputation builds.
Set Delays Between Sequence Steps
Why delays matter: Sending step 2 immediately after step 1 looks unnatural. Space out your sequence.
Best practices:
Wait 2–3 days between steps for cold outreach
Wait 5–7 days for nurture sequences
Adjust based on reply rates
How to set delays:
In your campaign, open the Sequence tab, click the step you want to adjust, and edit the wait delay (for example, change “Wait 1 day” to your desired number of days).
Understanding Sending Limits
What Are Sending Limits?
Your sending limit is the maximum number of emails you can send per day. This protects your domain reputation.
Default limits:
Gmail/Google Workspace: 500 emails per day (per account)
Outlook/Office 365: 300 emails per day (per account)
Custom domains: Varies by provider
Where to check your limit: Click your name in the bottom-left corner, then open Settings.
How the Algorithm Respects Limits
The algorithm automatically stops sending when you reach your daily limit. You won't accidentally exceed it.
Example:
Your limit: 50 emails per day
Your campaign has 200 leads
The algorithm sends 50 emails today, 50 tomorrow, 50 the next day, and 50 on day 4
Increasing Your Sending Limit
If you need to send more emails per day:
Warm up your domain first using lemwarm (2–4 weeks)
Verify your domain reputation is healthy (Google Postmaster Tools)
In Settings, open Sending limits and increase the maximum number of emails (use + / −) gradually.
Increase your limit step-by-step (e.g., from 50 to 75, then 100)
⚠️ Warning: Increasing limits too quickly damages reputation. Only increase after warm-up.
What Happens Next
When your campaign launches:
The algorithm calculates sending speed based on your schedule and limits
Emails are sent at consistent intervals throughout the day
Follow-up steps are triggered based on delays you set
Sending automatically stops at your daily limit
Monitor performance:
Check bounce rate (should be below 5%)
Track open and reply rates
Review sending speed in campaign analytics
Adjust schedule if needed
Best Practices
✅ Start slow: New domains should send 20–30 emails per day initially, then increase gradually.
✅ Match audience timezone: Send when your prospects are active (not at midnight).
✅ Space out emails: Reaching a new lead every 15–20 minutes is safe for most domains.
✅ Use lemwarm: Warm up new domains for 2–4 weeks before sending campaigns.
✅ Monitor bounce rates: If bounces increase, slow down sending immediately.
✅ Respect limits: Don't push your daily limit unless your domain is warmed up.
✅ Delay between steps: Wait 2–3 days between sequence steps for natural pacing.
Common Questions
Can I send faster than “every 20 minutes”? Yes, but only if your domain is warmed up and has a good reputation. Start slow and increase gradually.
What if I reach my daily limit mid-campaign? The algorithm stops sending automatically. Remaining emails are sent the next day.
Can I send on weekends? Yes, customize your schedule to include Saturdays and Sundays if your audience is active then.
Why is my campaign sending slower than expected? The algorithm may be protecting your domain due to high bounce rates, low open rates, or a new domain. Check your reputation.
Can I override the algorithm? No. The algorithm is designed to protect your deliverability. Manual overrides would damage your reputation.