Split a Lead List by Email Provider (Gmail, Outlook)
To split a lead list by email provider, upload it to the free bulk email provider lookup: it reads the MX records of every domain and labels each row Google Workspace or Gmail, Microsoft 365 or Outlook, Yahoo, Zoho, Proton or another provider. Filter the labels, download each segment, and verify and send each one on its own terms.
When the segments are ready, upload the list for 100 free checks, no card.
Why the provider matters
Mail providers answer a mailbox check in different ways, so one list produces different result mixes by segment:
| Segment | What verification can tell you |
|---|---|
| Gmail and Google Workspace | Gmail rejects unknown mailboxes with 550 5.1.1, so a per-mailbox answer is usually possible; a Workspace domain set to catch-all accepts everything |
| Microsoft consumer (outlook.com, hotmail.com, live.com, msn.com) | Currently risky: Microsoft refuses mailbox checks from our server's network |
| Microsoft 365 business domains | Depends on the tenant; behind a gateway they often come back risky |
| Yahoo, AOL | Hard to confirm; returned as risky, never valid |
| Business domains behind Proofpoint, Mimecast or Barracuda | Often catch-all, so risky |
For the detail, see checking if a Gmail address exists, verifying Outlook and Hotmail, why Yahoo is hard and verifying behind security gateways.
Step by step
- Run the lookup. Upload the CSV of addresses (or domains) to the bulk email provider lookup. Where a gateway hides the real host, SPF is used to label the row. For one domain in detail, use the email provider lookup.
- Download the split. Filter by provider label and save each segment as its own file.
- Verify the whole list on the verify page. Keep the provider label in your file so you can sort the results by it.
- Plan one send per segment. Gmail and confirmed-valid rows first. Microsoft consumer, Yahoo and gateway rows as small test batches, one segment at a time.
- Read each segment's bounce rate on its own. A blended number hides a bad segment.
Splitting for other reasons
If you only need equal-size files for sequencing, the email list splitter cuts a list by rows or file count in your browser, with every column kept.
What it costs
The lookup is free. The verification is where checks are spent: after the first 100 free, Starter is $9 a month for 2,500 emails, packs start at $15 for 10,000 checks and never expire, and Pro is $39 a month with the first 100,000 checks a month at full speed, then slower, never cut off. See pricing.
Verify the segments
Upload your list on the verify page: 100 free checks with a Google sign-in, no card.
Common questions
How do I split a list by email provider?
Upload a CSV of addresses or domains to the bulk email provider lookup. Each row is labelled by who receives its mail, and you can filter the results and download the split.
How can I tell if a domain uses Google or Microsoft?
Look up its MX records. Google Workspace and Gmail point to Google's mail hosts, and Microsoft 365 or Outlook to Microsoft's. A security gateway can hide the real host, which is why SPF is read as well.
Why split a list before verifying?
Because the result mix differs by provider, and you will want to send and measure each group separately.
Is the lookup free?
Yes, the provider lookup tools are free to use. Verifying the addresses uses your checks: the first 100 are free with a Google sign-in.
Check your list before you send
Real mailbox checks over SMTP, and nothing is sent to the address. Sign in with Google and your first 100 email checks are free, no card. Plans for bigger lists are on the pricing page.