Articles on: Deliverability

How to migrate without hurting your email deliverability ?

As part of migrating your contacts to systeme.io, several key steps must be followed to ensure a smooth transition from an external autoresponder. This includes the application of best practices in technical setup, legal compliance (especially regarding GDPR), and marketing.

1. Preparation and audit of your current database

A well-prepared list is essential for a successful migration. Here are the initial steps to follow:

Export your contacts in CSV format.
Review the available data: first name, last name, email, status (subscribed, unsubscribed), registration date, tags, etc.
Segment your contacts based on engagement (active/inactive) to avoid importing outdated email addresses.
Identify recent activity: if you’ve sent emails recently, focus on contacts who opened your messages in the last 30, 60, or 90 days.

2. Cleaning the database before import

Once your list is properly sorted, it’s crucial to ensure the quality of the email addresses it contains.

Here are the recommended best practices:

Remove duplicates, inactive, or invalid addresses.
Use filters in your previous email tool to clean your list. If such filters are not available, use an email verification service to avoid risky addresses (hard bounces, spam traps, etc.).
Keep proof of consent (opt-in) our team may request this.
Respect contact statuses: do not reactivate unsubscribed or inactive contacts.
Ensure that tags and segments are properly assigned.

Note: You can import unsubscribed contacts into your systeme.io account. They will automatically be assigned an "unsubscribed" status and will not receive any communication through the platform.

It is also essential to only import contacts who have explicitly consented to receive your emails, to remain GDPR-compliant and preserve your deliverability.

3. Importing "Student" contacts from your courses:

If you're importing contacts who participated in your courses but haven’t received emails from you in a while, the import process should be gradual.

Whenever a contact is added to a course in your systeme.io account, an automatic email is sent with a login link to access their course space.

To avoid a surge of bounced emails due to inactive addresses, we strongly recommend staggering the import.

4. Warming up your sending address or domain

When switching email providers, a warm-up process is necessary. This involves gradually training email providers to recognize and trust your new sending behavior, helping you maintain a good sender reputation and avoid landing in spam folders.

We explain the reasons for this in this help page.

Key warm-up steps:

Start by emailing your most engaged contacts.
Gradually increase the volume of emails sent each day.
Avoid sending large batches immediately, as this may trigger blocks or spam filtering by ISPs.

Tests and follow-up after migration

Send test campaigns to small segments.
Monitor key metrics: open rates, click rates, spam complaints, and bounce rates.
Avoid re-engagement campaigns to inactive contacts during the initial period.
Adjust your content or deliverability settings if needed.

Let's look together at an example of warming a list of over 5,000 contacts (also known as email warm-up).

This step is crucial to ensure good deliverability after a migration or a change of sending tool. It involves gradually sending emails to your contacts to establish a reliable sender reputation with major email providers (Gmail, Outlook, etc.).

Objective: Avoid your emails going to spam or being blocked by ISPs, starting with the most engaged subscribers.

Example Warm-Up Plan for a List of 5,000+ Contacts

This process is crucial for ensuring high deliverability after a migration. It helps build a reliable sender reputation with major email providers like Gmail, Outlook, etc.

Goal: Avoid spam filters and blocks by ISPs.

Suggested warm-up plan over 7 to 14 days:

Days 1–2: Send to 500 highly engaged contacts (opened/clicked within the last 30 days).
Days 3–4: Increase to 900 contacts, still highly engaged.
Days 5–6: Send to 1,500 contacts, including semi-engaged ones (opened within the last 60 days).
Days 7–9: Send to 2,500 - 4,000 contacts, including moderately active users.
Days 10–14: Send to the entire list, excluding long-term inactive addresses.

Here is another warming format:

Day	Sending volume	Target	Objective
Day 1	500	Very engaged contacts (open < 30 days)	Test reputation, validate deliverability
Day 2	900	Very engaged + addition of semi-engaged	Maintain high open rates
Day 3	1500	Engaged (open < 60 days)	Expand the base while monitoring the return
Day 4	2000	Engaged + some recent inactive	Monitor spam and bounce rates
Day 5	3000	Mixed public active/lightly inactive	Test sub-segments
Day 6	4000	Inactive < 90 days	Scale up carefully
Day 7	5000	Large public, except inactive > 120 days	Comprehensive but controlled approach
Day 8	6000+	All except very old inactive (> 6 months)	Stabilize daily sending
Day 9	100%	Total base, except unsubscribed/invalid	Return to normal cadence
Day 10	100%	Clean list, segmentation in place	End of warm-up – start of regular campaigns

Best Practices During the Warm-Up

1. Prioritize Your Most Engaged Contacts

Start your email sends with contacts who have recently opened or clicked your emails.

This sends a positive signal to Internet Service Providers (ISPs) by generating high open and click-through rates.

Use dynamic segments such as: Opened / Clicked in the last 30, 60, or 90 days.

2. Craft High-Quality Content

Quality content directly improves your deliverability.

Follow these key guidelines:

Use personalized and engaging subject lines.
Include clear and trackable links.
Avoid elements commonly flagged as spam:

Excessive capitalization in the subject line.
Overpromising or overly promotional language.
Unnecessary attachments.
Special characters or symbols in titles.

3. Monitor key indicators

Keep a close eye on your campaign performance indicators:

Open rate: > 20% is considered a good average.
Click-through rate: > 2%, depending on the type of campaign.
Bounce rate: < 2%.
Spam complaint rate: < 0.1%.

4. Remove problematic addresses

Regularly clean your list by removing inactive contacts to maintain high list quality.

Remove any contacts who haven’t shown activity (no opens or clicks) for more than 6 months.

On systeme.io, you have two options to do this:

5. Authenticate your sends

Ensure that SPF, DKIM and DMARC are properly configured for your domain. (this step is included in the data migration process unless you want to handle it yourself)
Use a dedicated sending domain (e.g., news@votreentreprise.com).
Create a Google Posmaster Tools account.

Your success is our priority. That’s why, at systeme.io, we continuously ensure the deliverability of your emails and tirelessly improve our services to maximize your results.

We provide you with a dedicated deliverability support service, available 7 days a week. Don’t hesitate to contact us if needed, our team is here to support you.

Bonus: Recommended Tools

Email validation tools: NeverBounce, BriteVerify, ZeroBounce.
Deliverability monitoring: GlockApps, Mail-Tester, Postmaster Tools (Gmail).

Related articles:

Updated on: 14/07/2025

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