Warming up your email accounts the right way is one of the best things you can do to improve deliverability.
It helps build a strong sender reputation, so your emails are more likely to land in the Inbox.
Let’s walk through the most important do’s and don’ts for email warm-up. It works best when you take a consistent approach and follow proven best practices.
Deliverability checks during warm-up
Warm-up and Campaign sending limits
Recommended warm-up settings
Add your email accounts to automatic warm-up. Here are the settings we recommend for best results.
Warm-up period
A warm-up needs to run long enough to have a real impact. If you start sending too early, you can lose the progress from the warm-up or make it take longer to reach good deliverability.
- 4 weeks: recommended for new domains and new accounts to prepare them for campaigns
- 2 weeks: reactivate account after a pause; improve the deliverability of accounts with issues
When to warm up new senders:
- Right after you set up accounts, before starting campaigns
When to warm up existing senders:
If you already started sending without warm-up, pause all active campaigns and do the warm-up period first.
- After a pause in outreach (the account hasn’t been used in campaigns for some time)
- Before increasing sending limits
- To fix existing deliverability issues
Warm-up strategy
Both new and existing email accounts should be warmed up. In the warm-up settings, choose a strategy based on your account.
For new accounts, use Progressive warm-up strategy:
- Starting volume: This is the number of emails we’ll send on the first day of the warm-up. Snovio recommends starting with 2 emails per day.
-
Daily volume increase: The number of emails added to the limit each day. Set it to 2 emails.
-
Daily sending goal: The maximum daily warm-up volume. Snovio recommends your warm-up goal 40 emails per day.
For existing accounts, use a Steady warm-up strategy:
- Emails per day: Snovio recommends setting this limit to 40 emails. This number cannot be higher than your email account’s Messages per day limit.
Warm-up pool
Turn on the Premium sender pool in Snovio to warm up your account using business email addresses.
Choose the providers you want to use for provider-specific warm-up. This way, your emails are sent to the same providers, which helps improve deliverability by provider (Gmail/Outlook).
Warm-up email content
In Email content settings, choose between the options depending on your warm-up goal.
Specific template
You can add your own email template that you plan to use in real campaigns. Warm-up will use this exact template to improve deliverability.
Because the same content is used, keep the daily warm-up limit lower—around 5–10 emails per day.
Repetitive content can look suspicious. To make the warm-up less repetitive, use Spintax.
You can insert spintaxes from the Variable menu in the Email content settings (it's available only in Specific content type).
- Bad Spintax uses
{Hi|Hey|Hello} — a simple change in the greeting will have little to no impact.
{Thanks|Thanks a lot} — micro-variations will have no effect.
I {want|would like} to talk — a rephrase that doesn’t change the sentence at all.
We {accelerate|turbocharge|10x} growth — adding hype synonyms to Spintax increases the risk of triggering spam filters.
- Good Spintax uses
Openers (different sentence structure, same intent):
{Reaching out|Following up} about {your outbound results|reply rates}.
Noticed you are {hiring AEs|increasing SDRs}—thought this might help.
I work with {teams like|companies similar to} yours on {reply rate|meetings booked}.
Rephrase problem + value:
Recently helped {Acme|Company} {double meetings|reduce bounces by 35%}.
Seeing {low reply rates|slow pipeline} from cold emails? We help teams {improve replies by 20–30%|book more first meetings} by {clarifying ICP + cleaning data|fixing list quality + email copy}.
CTA:
{Happy to share a 2-min breakdown of what worked |Are you open for a quick run-down?}
If not the right fit, mind pointing me to {the right person|who does outbound}?
AI-generated emails
This option is best suited for the first warm-up of a new account or for restoring reputation after a period of inactivity.
AI-generated warm-up emails have unique content to avoid repetitiveness. To make them look less generic, we add manually pre-written subject lines and phrases.
Warm-up statistics
Monitor Deliverability score on the warm-up dashboard to decide whether to extend or adjust your warm-up. If inbox score is lower than 80% → extend warm-up until the score improves.
If deliverability shows bad results during warm-up, decide the best approach based on your account:
- New mailbox:
If it's a new account with little to no sending history, continue the warm-up. If you stop it before completing a 4 week warm-up, it may impact your sender reputation. Check your mailbox health with the deliverability tests and review DNS records.
- Existing mailbox:
If your email account is already active and is used to send campaigns, don’t pause warm-up. Check your mailbox health with the deliverability tests, review DNS records, and reduce email sending limits while warm-up continues.
Deliverability checks during warm-up
Simulation sending is a must for every stage of your outreach. You can do it with Snovio’s all-in-one checker Deliverability Check.
Test frequency
- After warm-up (Before launching any campaign)
- At least once a week while campaigns are active
- Every time before you increase the sending limit
Metrics to monitor
Check these results after running tests:
Domain health
75% is the minimum acceptable score to start campaigns; 100% score is recommended before you increase sending limits.
Inbox placement
90% inbox across target providers (Gmail/Outlook): the sender can be used.
80% inbox: fix any underlying issues. Rebalance more volume from campaigns into warm-up
Spam rate
5% or more spam: Don’t use this sender for campaign → run on the warm-up only
Warm-up during campaigns
When you start outreach, don’t use your full daily limit for campaigns only.
Warm-up and campaign sending limits
Remember, emails sent for warm-up count as real emails. To get the best deliverability, keep your total daily sending (warm-up + campaign) at 50 emails/day or less.
For your first campaign after warm-up, Snovio recommends these limits:
-
40 warm-up emails/day
-
10 campaign emails/day
Warm-up and campaign sending limits are set separately in the settings, but they both count toward your total daily limit per email account.
- Set the warm-up limit in the warm-up settings
- Set the campaign sending limit in your email account settings
If deliverability stays above 90%, gradually shift limit from warm-up to campaign:
-
Each week, add 5 emails/day to campaign sending
For your active campaign sending phase, Snovio recommends these limits for campaigns and warm-up:
-
30 campaign emails/day
-
20 warm-up emails/day
- If you notice deliverability issues, reduce campaign sending and increase warm-up
Deliverability protection
Your sender reputation changes based on your email activity. Cold outreach can bring negative signals, like bounces or spam reports. Warm-up helps keep steady activity and adds positive signals.
Run warm-up always. Keep warm-up running when you’re not sending campaigns. Long breaks in sending can hurt your reputation, and you may need to warm up again before your next campaign.
-
Keep warm-up active during campaigns and between campaigns
-
Avoid long gaps in sending
-
When campaigns are active, split your daily limit between campaign and warm-up
-
When campaigns are paused, use your full daily limit for warm-up
-
On days when you send fewer emails than usual, add warm-up emails to keep activity steady
Mailbox rotation
Warm up more mailboxes to always have additional senders in your back-up. When you need to reach more prospects, add warmed-up senders from your back-up pool, not completely new accounts.
Use mailbox rotation to increase your total limits safely. Add as many accounts as your need to hit your sending goal. Every mailbox in rotation should use the recommended limits.
Review performance for each mailbox in the Reports dashboard.
Sorry about that 😢
How can we improve it?