How to Stop Sales Emails From Vendors and Suppliers

If you are looking for how to stop sales emails from vendors, the hard part is not the email from a name you have never seen — it is the company where you have a real supplier relationship. Block the wrong address and you miss a shipment notice, an invoice, or a contract renewal.

The approach that works treats this as two separate problems: protecting the threads you need, then stopping the ones you do not. This guide follows that order — keep-list first, block-list second.

Before You Start: Build Your Keep-List#

Vendor inboxes are messy because prospecting and legitimate business often arrive from the same company domain. The account manager handling your purchase orders and the growth rep running cold outreach may both send from @supplier.com — and a domain-level block catches both.

Spend five minutes before you create any rule. Open your Sent folder and look at every vendor address you have replied to in the last 90 days. Add each of those addresses to your contacts or safe senders list now, before any filter runs.

• Note any supplier who sends from a marketing subdomain. Some companies split transactional and promotional mail across domains — mail.supplier.com versus the main supplier.com, for example.
• Newsletters you signed up for intentionally belong on the keep-list. Route them to a folder if you want, but do not block the sender address.
• If a supplier uses a shared platform address — [email protected] — add that specific address to contacts rather than relying on the company name.

Steps to Stop Vendor Sales Emails#

Work through these steps in order. Unsubscribing is the cleanest solution when it works; filtering and blocking are the escalation path when it does not.

1. 1

   Unsubscribe from US-based senders first

   US commercial email — including B2B prospecting — is covered by the CAN-SPAM Act. Senders must honor opt-out requests within 10 business days and cannot require more than replying to an email or visiting a single webpage. Look for an unsubscribe link in the message footer and click it. If a commercial email from a US sender has no unsubscribe link at all, that is itself a CAN-SPAM violation you can report to the FTC at reportfraud.ftc.gov.

2. 2

   Create a domain-level filter for persistent prospectors

   A sender block matches one address. A domain filter catches every rep at that company, current and future. In Gmail, enter 'from:@company.com' in the search bar, open search options, click Create filter, and choose Delete it or Skip the Inbox. In Outlook web, go to Settings, then Mail, then Block or Allow, and add the company domain to the Blocked Senders field.

3. 3

   Block individual senders for one-off contacts

   For single addresses that are not part of a repeating company pattern, use your client's block feature. In Gmail, open the message, click the three-dot menu at the top right, and select Block [sender name] — future mail from that address goes to Spam. In Outlook, right-click the message, choose Junk, then Block Sender.

4. 4

   Report as spam when a sender bypasses your filter

   If a vendor routes around your rule by sending from a new address, mark the email as spam rather than just deleting it. Your mail provider pools spam reports as a signal to improve filtering at the domain level, which tightens the net for that vendor's future messages regardless of which address they use.

5. 5

   Review your filters at the 30-day mark

   Check whether any filter is catching supplier mail you actually need, and whether any prospecting is still reaching your inbox. Most filter drift happens in the first month. Adjust the rule — tighten a domain pattern, add a safe-sender exception — rather than rebuilding from scratch.

Gmail vs. Outlook: What Each Option Actually Does#

The mechanism differs by platform, and the difference matters when you decide which tool to reach for. In Gmail, blocked mail goes to Spam — it is not deleted and you can review it. In Outlook, it goes to Junk. Domain-level controls also behave differently in each client.

When Blocking Does Not Hold#

The most common failure is address rotation. A vendor's sales platform cycles through [email protected], [email protected], and [email protected]. Each new address bypasses the block you set on the previous one.

The fix is moving from address-level blocks to domain-level filters. A filter for @company.com matches any sender at that domain regardless of the local address part. If the vendor also uses a separate marketing subdomain, create a second filter for that pattern.

If a sender is rotating the domain itself — using a different company name or domain with each email — no standard inbox rule will reliably keep up. Report those messages directly to your provider's abuse team. That behavior is phishing-adjacent and warrants escalation beyond filter rules.

A Faster Way to Keep Vendor Prospecting Out#

The five steps above solve the problem you have today. They do not stop new vendors from finding your address next month via a conference registration, a LinkedIn scrape, or a purchased contact database. The supply of new senders is not finite.

AI Emaily's cold-email filter identifies prospecting email by sender behavior and domain pattern — not just the single address that sent this one — so when a vendor's platform rotates addresses, the filter catches the category rather than resetting. The Rules Brain can also auto-route legitimate supplier threads to labeled folders before they reach your main inbox, keeping the keep-list you built above current without manual upkeep. We build AI Emaily.

The manual approach is the right starting point for clearing the backlog you have now. This is what running the same protection continuously looks like.