# What is graymail, and how is it different from spam?

URL: https://iblockspam.com/blog/graymail-bulk-email-vs-spam
Last updated: 2026-10-16
Published: 2026-10-16
Topic: Email security basics
Author: iBlockSpam Team

> Graymail is bulk email you once signed up for. Learn how it differs from spam, how Microsoft 365 and Gmail score and sort it, and how to clear it from inboxes.

## Short answer

Graymail is bulk email such as newsletters, promotions and notifications that you once agreed to receive but may no longer want. Spam is unsolicited and unwanted by everyone. Microsoft 365 calls graymail bulk mail and scores it with a bulk complaint level from 0 to 9. Unsubscribe from graymail; report and block spam.

Not everything clogging an inbox is spam. Much of it is mail people once signed up for: software newsletters, webinar invitations, supplier promotions, "your weekly summary" notifications. The industry term for it is **graymail**, and filters treat it differently from spam because it isn't unwanted by everyone.

This guide defines graymail, shows how Microsoft 365 and Gmail detect and sort it, and gives users and admins a clear way to deal with it.

## What is graymail?

**Graymail** is bulk email from a legitimate sender that the recipient agreed to receive at some point, but may no longer want. Microsoft uses the same idea in its own documentation: "Messages from a bulk sender are known as *bulk mail* or *gray mail*" ([Microsoft Learn](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-bulk-complaint-level-bcl-about)).

Common examples:

- Newsletters from software vendors and industry groups.
- Retail and supplier promotions.
- Event and webinar invitations.
- Social network and app notifications.
- Automated reports nobody reads any more.

The problem is that it's personal. Microsoft puts it this way: "some users want bulk email messages (and in fact, they have deliberately signed up to receive them), while other users consider bulk email to be spam" ([Microsoft Learn](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-spam-vs-bulk-about)).

## What is the difference between graymail, spam and phishing?

| | Graymail (bulk mail) | Spam | Phishing |
|---|---|---|---|
| Did you agree to it? | Usually, at some point | No | No |
| Sender | A real, identifiable organization | Often hidden or forged | Impersonates someone you trust |
| Does unsubscribe work? | Usually yes | Often not, and clicking can be risky | Never click |
| Main harm | Clutter and lost attention | Clutter, scams, malware | Stolen credentials, payment fraud |
| What to do | Unsubscribe, or sort it into a folder | Report as junk, block | Report it, and tell IT if you clicked |

Microsoft defines **spam** as "an unsolicited and universally unwanted message" ([Microsoft Learn](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-spam-vs-bulk-about)). If you aren't sure which category a message is in, our guide on [why an email landed in spam](https://iblockspam.com/blog/why-did-this-email-land-in-spam) explains how to read the verdict.

## How do filters detect bulk email?

### Microsoft 365: the bulk complaint level

Microsoft 365 gives inbound mail from bulk senders a **bulk complaint level (BCL)**, a score from 0 to 9 ([Microsoft Learn](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-bulk-complaint-level-bcl-about)). It appears as the `BCL` field in the `X-Microsoft-Antispam` header ([Microsoft Learn](https://learn.microsoft.com/en-us/defender-office-365/message-headers-eop-mdo)):

| BCL | Meaning |
|---|---|
| 0 | Not from a bulk sender |
| 1 to 3 | Bulk sender that generates few complaints |
| 4 to 7 | Bulk sender that generates a mixed number of complaints |
| 8 to 9 | Bulk sender that generates a high number of complaints |

Mail at or above the policy's bulk threshold gets the bulk action. The threshold is 7 in the default policy, 6 in the Standard preset and 5 in Strict. By default that action is the Junk Email folder, or quarantine in Strict. Our guide to [spam scores](https://iblockspam.com/blog/what-is-a-spam-score) compares BCL with other scores.

### Gmail: inbox categories

Gmail sorts mail into tabs rather than scoring it publicly. **Promotions** holds "deals, offers, and other promotional emails", **Social** holds messages from social networks, **Updates** holds "automated confirmations, notifications, statements, and reminders", and **Forums** holds mailing lists ([Gmail Help](https://support.google.com/mail/answer/3055016)). Dragging a message to another tab teaches Gmail where similar mail belongs.

### The headers that mark list mail

Legitimate bulk mail usually carries unsubscribe headers. [RFC 2369](https://www.rfc-editor.org/rfc/rfc2369.html) defines `List-Unsubscribe`, and [RFC 8058](https://www.rfc-editor.org/rfc/rfc8058.html) adds one-click unsubscribe. An example from a newsletter, with illustrative values:

```text
List-Unsubscribe: <https://news.example.com/unsub/a1b2c3>, <mailto:unsub@news.example.com>
List-Unsubscribe-Post: List-Unsubscribe=One-Click
X-Microsoft-Antispam: BCL:5;
```

Gmail and other mail apps can use these headers to show their own **Unsubscribe** button. Paste a message's headers into the [Email Header Analyzer](https://iblockspam.com/tools/email-header-analyzer) to see them.

## Why are senders being pushed to make graymail easier to leave?

Mailbox providers now require it. Google's [email sender guidelines](https://support.google.com/mail/answer/81126) say that senders of more than 5,000 messages a day to Gmail accounts must support one-click unsubscribe for "marketing messages and subscribed messages" and "include a clearly visible unsubscribe link in the message body". They must also keep the spam rate reported in Postmaster Tools below 0.30%, and Google recommends staying below 0.10%.

That's good news for recipients: for most legitimate graymail, unsubscribing works and is safe. If you send newsletters yourself, our guides to [one-click unsubscribe](https://iblockspam.com/blog/one-click-unsubscribe-rfc-8058) and the [Gmail, Yahoo and Microsoft bulk sender rules](https://iblockspam.com/blog/gmail-yahoo-microsoft-bulk-sender-requirements) cover what you must do, and the [Bulk Sender Requirements Checker](https://iblockspam.com/tools/bulk-sender-checker) tests your domain.

## How do I reduce graymail in Microsoft 365?

Admins have four levers, at the time of writing (October 2026):

1. **Check the bulk threshold.** In `https://security.microsoft.com/antispam`, each inbound policy has a **Bulk email threshold** slider. Lower numbers treat more mail as bulk. The **bulk senders insight** in the same place simulates how much mail each threshold would catch ([Microsoft Learn](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-policies-configure)).
2. **Confirm bulk actions are on.** The PowerShell-only `MarkAsSpamBulkMail` setting is `On` by default. If someone turned it off, BCL is stamped but no action is taken.
3. **Turn on Bulk moves enabled.** This delivers promotional bulk mail below the threshold to a **Promotions** folder in supported Outlook versions. Microsoft says that as of July 2026, bulk messages "that are promotional in nature" get the **Promotions** tag automatically. The setting is currently off in the Standard and Strict presets, so users covered by presets need a separate policy ([Microsoft Learn](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-bulk-complaint-level-bcl-about)).
4. **Tell users to unsubscribe.** Microsoft's own advice is easy to overlook: if the messages "are from reputable senders that pass spam filtering, have the user check for an unsubscribe option".

Don't push the threshold too low to cut clutter. Supplier notices and event confirmations are bulk mail too, and you'll create [false positives](https://iblockspam.com/blog/false-positives-legitimate-email-flagged). Our [anti-spam policy guide](https://iblockspam.com/blog/microsoft-365-anti-spam-policies) covers the related settings.

## How do I reduce graymail in Gmail and Google Workspace?

Gmail's tabs do most of the work. Users can:

- Keep the **Promotions**, **Social** and **Updates** tabs turned on, and drag misplaced messages between tabs.
- Use the **Unsubscribe** option Gmail shows next to the sender for list mail.
- Block a sender that won't stop; future messages go to Spam.

Admins can review spam settings in our [Gmail spam settings guide](https://iblockspam.com/blog/gmail-spam-settings-google-workspace). Gmail doesn't expose a bulk score you can tune the way Microsoft's BCL threshold works.

## Should users unsubscribe or report graymail as spam?

Use this checklist:

1. **Do you recognize the sender and remember signing up?** Unsubscribe.
2. **Is it a real company you never signed up with?** Use its opt-out once. If it keeps coming, block it and report it as junk.
3. **Is there no identifiable company, or does it look like a scam?** Don't click anything. Report it as spam or phishing.
4. **Do you want it, but not in the inbox?** Use the Promotions folder or tab, or an inbox rule.

Reporting newsletters you signed up for as spam isn't ideal. Complaints feed sender reputation, which is what Google's 0.30% spam-rate limit measures. Our guide on [whether it's safe to unsubscribe from spam](https://iblockspam.com/blog/is-it-safe-to-unsubscribe-from-spam) covers the risky cases.

## How can a business cut graymail at the source?

Most graymail arrives because someone signed up. A few habits stop it piling up in the first place:

- **Use a role address for vendor portals and trials.** Sign up for software trials, supplier portals and trade shows with an address such as `purchasing@` or `it@`, routed to a shared mailbox, rather than a personal inbox.
- **Untick marketing boxes.** Event and download forms often pre-tick "send me updates". Clear them unless you want the newsletter.
- **Unsubscribe when a project ends.** When a trial, conference or supplier relationship is over, unsubscribe from its lists the same week.
- **Clean up during offboarding.** A leaver's mailbox keeps receiving every list they joined. Our [employee offboarding guide](https://iblockspam.com/blog/employee-offboarding-email-security) covers what to do with it.
- **Review automated reports.** Scheduled reports from internal systems are graymail too. Ask owners once a year whether anyone still reads them.

None of this needs a filter. It's simply the cheapest way to keep inboxes readable.

## When does an MX-level filter help with graymail?

Built-in tools are often enough for graymail: Microsoft's BCL threshold and Promotions folder, and Gmail's tabs. A filter at the MX level, which receives your mail before your mailbox does, adds most when you want one policy for every mailbox and alias, and want users to manage what's held without filing a ticket.

iBlockSpam gives every user a personal quarantine with scheduled digests (hourly, daily, a chosen weekday or custom), plus approved and blocked sender lists, so users can release a newsletter they want or leave the rest. See [quarantine and digests](https://iblockspam.com/features/quarantine-and-digests) for how it works, and [pricing](https://iblockspam.com/pricing) for per-domain plans.

## Next steps

- Look up the `BCL` value in a few newsletters with the [Email Header Analyzer](https://iblockspam.com/tools/email-header-analyzer) to see how Microsoft scores your graymail.
- Review your bulk threshold and run the bulk senders insight before you change it.
- Ask staff to spend ten minutes unsubscribing from lists they no longer read.
- If you send newsletters, run the [Bulk Sender Requirements Checker](https://iblockspam.com/tools/bulk-sender-checker) on your domain.
- If you want per-user quarantine digests across a whole domain, see [iBlockSpam pricing](https://iblockspam.com/pricing).

Browse more [email security basics](https://iblockspam.com/blog/topic/basics).

## Frequently asked questions

### Is graymail the same as spam?

No. Spam is unsolicited mail nobody wants. Graymail is bulk mail from a real sender that the recipient usually agreed to receive at some point, such as a newsletter or store promotion. Microsoft describes bulk email as harder to classify because some users want it and others consider the same messages spam.

### Which bulk complaint level counts as graymail in Microsoft 365?

Any BCL from 1 to 9 means the message came from a bulk sender. Microsoft groups 1 to 3 as few complaints, 4 to 7 as a mixed number, and 8 to 9 as many. Messages at or above your policy threshold, 7 by default, 6 in Standard and 5 in Strict, get the bulk action.

### Does reporting a newsletter as spam hurt the company that sent it?

Yes, it can. Mailbox providers track complaints. Google asks bulk senders to keep the spam rate reported in Postmaster Tools below 0.10% and never reach 0.30%, and Microsoft's bulk complaint level reflects complaints too. If you signed up, unsubscribing is fairer to the sender and just as effective for you.

### Can Outlook move newsletters to their own folder automatically?

Yes, in supported versions. Microsoft 365 admins can turn on Bulk moves enabled in an anti-spam policy, which delivers promotional bulk mail below the bulk threshold to a Promotions folder. At the time of writing (October 2026), the setting is off in the Standard and Strict preset policies, so users covered by presets need a separate policy.

### Why does graymail matter for email security?

Mostly because of noise. When inboxes fill with promotions, people skim, and important or suspicious messages get less attention. Attackers also copy the look of newsletters and shipping notices. Reducing graymail makes real business mail stand out and makes odd messages easier to notice.

## Sources

- [Microsoft Learn: What's the difference between junk email and bulk email?](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-spam-vs-bulk-about)
- [Microsoft Learn: Bulk email detection and the bulk complaint level (BCL)](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-bulk-complaint-level-bcl-about)
- [Microsoft Learn: Configure spam filter policies](https://learn.microsoft.com/en-us/defender-office-365/anti-spam-policies-configure)
- [Gmail Help: Organize your emails into categories](https://support.google.com/mail/answer/3055016)
- [Google: Email sender guidelines](https://support.google.com/mail/answer/81126)
- [RFC 8058: Signaling One-Click Functionality for List Email Headers](https://www.rfc-editor.org/rfc/rfc8058.html)
- [RFC 2369: The Use of URLs as Meta-Syntax for Core Mail List Commands](https://www.rfc-editor.org/rfc/rfc2369.html)

## Free tools for this guide

- [Email Header Analyzer](https://iblockspam.com/tools/email-header-analyzer): Trace hops and authentication results — runs entirely in your browser.
- [Bulk Sender Requirements Checker](https://iblockspam.com/tools/bulk-sender-checker): Check your domain against the Gmail, Yahoo and Outlook.com bulk sender rules that DNS can show, with a checklist per provider.
- [Email Deliverability Test](https://iblockspam.com/tools/deliverability-test): Send one email and see its SPF, DKIM and DMARC results, reverse DNS, blocklists, TLS and spam verdict.

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Source: iBlockSpam, https://iblockspam.com/blog/graymail-bulk-email-vs-spam (this is a Markdown copy; the HTML page is canonical). Quote with attribution and a link. Site index for AI assistants: https://iblockspam.com/llms.txt