Warm-up process

Hi there,

Thanks for bringing up this question, warming up your sending domain is a crucial step to protect your deliverability and make sure your campaigns reach your audience effectively. Here’s a clear, step-by-step approach you can follow.

Step 1: Export your subscribers

To warm up your domain, first check if your audience is already uploaded to Omnisend (Audience → Contact list). If it is not uploaded yet, you can move directly to Step 2 to work on your CSV files. If it’s already in Omnisend, you’ll need to export your subscribed contacts first.

If you already have engagement metrics like opens & clicks for your customer base in Omnisend, target the most engaged audiences first (create segments based on engagement filters).

During the first stages of the warmup, you will need to focus on sending emails only to your most engaged audience. After the first week, you can start mixing engaged with unengaged contacts, but make sure the ratio is always in favor of the engaged ones.

If you are a new sender without engagement metrics yet, proceed with the steps described below.

Here’s how to export your subscribers from Omnisend:

1. Go to Audience → All contacts.
2. Click Export → New Export.
3. Under “Select contacts to export,” choose contacts by email subscription status → Subscribed.
4. Click Export and download the CSV.

This file is your clean, permission-based audience, the best starting point for warming up.

Step 2: Split the file into daily Batches

Now split your exported list into smaller batches so you can slowly ramp up the sending volume day by day.

You can use Google Sheets, Excel, or other online CSV splitter tools. Each batch will be used for one day’s campaign. You only need email addresses in your future files; everything else can be removed from the lists.

Example (manual split in Excel or Google Sheets)

Let’s say you exported 10,000 contacts and you’re following the Medium Plan (different plans are described in the table), which starts with 1,000 emails on Day 1.

1. Open the exported CSV in Google Sheets or Excel.
2. Keep only the “Email” column (delete the others if needed).
3. Select the first 1,000 rows (not including the header).
4. Copy and paste into a new sheet or file → Save as warmup_day1.csv.
5. Select the next 1,500 rows → Save as warmup_day2.csv.
6. Continue with the next daily volumes from the warm-up table.

I hope this helps you start your warmup process smoothly and with minimal risk to your deliverability. If you’d like, share your sending schedule or engagement data with us, we’ll be happy to review and suggest the safest possible ramp-up plan for your specific audience.