How a dirty list damages your domain
Mailbox providers such as Yandex 360, Mail.ru and Google judge a sender partly by delivery failures. When messages repeatedly go to addresses that do not exist, providers can reduce delivery for the whole domain—not only for cold outreach, but also for correspondence with current customers.
Two address types need special treatment. Spam traps are addresses used to identify careless sending. Catch-all domains accept mail for almost any address, so a technical check may report an invented inbox as valid even when no real recipient exists.
Cleaning the list before launch is usually less costly than rebuilding a damaged sending reputation. It also prevents your team from spending time on companies that never had a reachable contact.
What the service includes
Send us a CSV, Excel file or CRM export. You receive the full list back with a status for every address and a clear reason for each exclusion.
- Syntax and deduplication. We remove malformed addresses, duplicate records and obvious formatting errors. Company records are consolidated so the same organisation is not contacted twice by accident.
- Domain and mail-routing check. We identify domains that no longer exist or cannot accept email.
- Mailbox-status check. We query whether the receiving server is prepared to accept mail for a specific address, without sending a real message.
- Catch-all review. Catch-all domains are marked separately and assessed using the address pattern, role and available business context.
- Risky and role-address review. We flag known risks and unsuitable functional inboxes. Addresses such as info@ or sales@ are reviewed rather than automatically discarded, as they can be legitimate B2B contact points.
What level of exclusions is normal
The exclusion rate depends primarily on where the list came from. A recently built, segment-specific list is usually cleaner than an old CRM export, where people have changed jobs, companies have closed and domains have expired.
| List origin | Typical outcome | What is usually removed |
|---|---|---|
| Fresh segment-specific research | Limited exclusions | Typos, duplicates and inactive domains |
| Older working list | Noticeable exclusions | Former employees and closed companies |
| Old CRM export or purchased list | High exclusions | The above, plus higher trap and relevance risk |
A meaningful reduction in an old list is not a failure of validation; it is a record of what would otherwise have produced bounces. Equally, treating every catch-all domain as invalid can remove live B2B companies, which is why those records need separate handling.
Timing and what we need from you
A standard list of up to several tens of thousands of addresses is normally processed within one to three business days. Larger files and lists with many catch-all domains can take longer because ambiguous records require review.
- Your list in CSV or Excel format, with its origin and collection date
- Your target segment: the companies and job roles you need to reach
- A responsible contact who can answer classification questions during the business day
If you do not yet have a list, start with <a href="/en/services/lead-list-building/">B2B lead list building</a> and then validate it before sending. If the list is clean but messages still land in spam, the issue may be broader outreach infrastructure; a <a href="/en/free-audit/">free outreach audit</a> can identify the weak point.
How we measure the result
The useful result is not the number of deleted addresses. It is how the cleaned list behaves in real sending: accepted mail, bounce rate and the quality of catch-all classifications.
Across our campaigns, 97.7% of addresses accepted email and the bounce rate was 2.3% across 3,224,000 emails sent. A zero-bounce promise is not credible: some residual uncertainty remains, particularly with catch-all domains.
You receive the entire annotated list, including excluded records and their reasons. An invalid address does not mean the company should be removed from your market map; it may mean a different contact needs to be found.
When list verification is not the right service
Verification cannot make a weak offer relevant or turn an unfocused list into a target segment. It answers whether an inbox is reachable, not whether the recipient needs what you sell.
- Your list was not built for your target segment. Start with a proper selection of companies and roles.
- You plan a small, one-off send. A manual check or simple tool may be more economical.
- You send through infrastructure you do not control. Delivery issues may need to be addressed within that platform.
- You want to measure opens. List verification does not measure interest or engagement.
If you are unsure whether the bottleneck is the list, the domain or the message, begin with a <a href="/en/free-audit/">free cold outreach audit</a>. We will assess the system as a whole and point to the constraint.
How pricing works
Pricing depends on list size, the share of catch-all domains and the depth of review required. Verification as a standalone service is priced differently from verification included in a full campaign launch.
See <a href="/en/pricing/">outreach pricing for Russia and CIS</a> for the current service structure and budget context.