# What is snowshoeing in email and SMS, and how to avoid it

> Snowshoeing spreads messages across many numbers, IPs or domains to dodge filters. What CTIA and Spamhaus say, and how to use several senders honestly.

By Wade, Duckrow's research desk (a house pen name). Published 2026-10-21, updated 2026-10-21.

Snowshoeing is spreading similar messages across many phone numbers, IP addresses or domains so no single sender carries enough volume to trip a filter. CTIA's messaging principles tell texting senders not to do it, and Spamhaus lists snowshoe ranges on its blocklist. Filters track reputation per domain, IP and number, so spreading thin rarely hides a bad list.

## What does snowshoeing mean for texting?
Sending similar texts from many numbers to stay under each number's limits. CTIA's Messaging Principles and Best Practices (May 2023, checked October 21, 2026) say, in section 5.5.2:

"Message Senders should not engage in Snowshoe Messaging, which is a technique used to spread messages across many sending phone numbers or short codes. Service Providers should also take measures to prevent Snowshoe Messaging."

The same section leaves room for real needs: "Messaging use cases that require the use of multiple numbers to distribute "similar" or "like" content may require special arrangements between Message Senders and Service Providers." In practice that means every number in a pool is registered under your business's campaign with the carriers, through your texting provider.

## What does snowshoeing mean for email?
Spreading bulk mail across many IP addresses and domains, often with thin or changing sender details. Spamhaus, which runs widely used blocklists, names it in the listing criteria for its Spamhaus Blocklist (checked October 21, 2026): "Snowshoe spam style configurations, particularly ranges and domains with poor or frequently changing identification."

Mailbox providers count in ways that make spreading less useful than it looks. Google says "Gmail tracks volume, feedback, and limits per domain and IP address", and counts mail from a primary domain and its subdomains together toward its 5,000-a-day bulk sender line. Spam reports still pile up on each domain you use.

## Is using several mailboxes or numbers snowshoeing?
Not by itself. Both sources describe a purpose (getting around filters) and a pattern (weak or changing identity). Here is how the two look side by side:

| Honest spreading | Snowshoeing |
| --- | --- |
| Every mailbox and number clearly belongs to your business | Senders with thin, rotating or lookalike identities |
| Each lead hears from one sender for the whole conversation | One campaign blasted from many senders at once |
| Every texting number registered under your campaign | Unregistered numbers added as others get filtered |
| Volume set by how your list reacts | Volume set to stay just under each filter's line |
| Domains kept and repaired when reputation dips | Domains dropped and replaced as they burn |

## How do you spread volume without snowshoeing?
1. Keep each lead on one mailbox and one number from the first message to the last.
2. Use your real business name in every From line, signature and text.
3. Register every texting number under your business's campaign before it sends.
4. Add senders because your list is growing, and keep each sender's volume steady.
5. Watch spam reports and opt-outs per domain and per number, and fix the list before adding senders.
6. Never use a rented or shared list. CTIA says opt-ins "should not be transferable or assignable."

This post explains carrier and blocklist practice and is not legal advice. CASL and US texting law set separate consent rules on top.

## How does Duckrow handle several senders?
- Email: new leads go to the least-used mailbox, and each lead stays on that mailbox for every follow-up, in the same thread. Each mailbox has its own daily cap.
- Texting runs through Textually, our texting product. Each business texts from its own Textually workspace with its own carrier registration, and Textually keeps each person on the number that first texted them.
- A reply on any channel ends that lead's sequence, so nobody keeps hearing from other senders after answering.

## Questions
### Is snowshoeing illegal?
The US and Canadian laws we read don't name it. It breaks CTIA's texting principles, which carriers enforce, and Spamhaus lists snowshoe ranges on its blocklist. This is general information and not legal advice.

### Does rotating domains help cold email deliverability?
It spreads volume, and Gmail still tracks reputation per domain and IP, counting subdomains with their primary domain. Rotating to escape spam reports is the pattern blocklists look for.

### Can I use several numbers for one texting campaign?
Yes, if every number is registered under your campaign. CTIA says using many numbers for similar content may need special arrangements with your provider, so ask yours first.

## Sources
- CTIA: Messaging Principles and Best Practices, May 2023 (checked October 21, 2026): https://api.ctia.org/wp-content/uploads/2023/05/230523-CTIA-Messaging-Principles-and-Best-Practices-FINAL.pdf
- Spamhaus: Spamhaus Blocklist and listing criteria (checked October 21, 2026): https://www.spamhaus.org/blocklists/spamhaus-blocklist/
- Google: Email sender guidelines (checked October 21, 2026): https://support.google.com/a/answer/81126
- Google: Email sender guidelines FAQ (checked October 21, 2026): https://support.google.com/mail/answer/14229414

Page: https://duckrow.ai/blog/what-is-snowshoeing-email-sms