How do you set the bulk complaint level (BCL) threshold in Microsoft 365?

Every Microsoft 365 anti-spam policy has a slider called Bulk email threshold. It decides how much newsletter and marketing mail reaches the inbox, and it's one of the few spam settings admins are encouraged to tune. Move it carelessly and you either flood inboxes or bury mail people asked for.

This guide covers how to read the bulk complaint level, test a new threshold before you change it, and set it in the portal or PowerShell. For the difference between bulk mail and spam, read graymail vs spam first.

What is the bulk complaint level (BCL)?

The bulk complaint level (BCL) is a score from 0 to 9 that Microsoft 365 gives inbound messages from bulk senders. Microsoft says "a higher BCL value indicates a bulk message is more likely to exhibit undesirable spam-like behavior" and that it uses "both internal and external sources" to set the value (Microsoft Learn).

A bulk sender is anyone sending the same message to many recipients: newsletters, promotions, event invitations, SaaS notifications. The BCL measures how much recipients complain about that sender, not whether the mail is malicious. Phishing is caught by other filters.

What is the default bulk email threshold?

The bulk email threshold is the BCL at which the policy's bulk action fires. Mail scored at or above it gets the Bulk compliant level (BCL) met or exceeded verdict. The label really does say "compliant", not "complaint".

Values and actions at the time of writing (October 2026), from Microsoft's recommended settings:

So with the default threshold of 7, messages with BCL 7, 8 or 9 go to Junk Email. BCL 6 and below reach the inbox.

One hidden switch overrides all of this. MarkAsSpamBulkMail is a PowerShell-only setting that's On by default. If it's Off, Microsoft says the message "is stamped with the BCL, but no action is taken" and the threshold and action "are irrelevant" (Microsoft Learn). Check it before you tune anything:

Get-HostedContentFilterPolicy |
  Format-Table Name,BulkThreshold,BulkSpamAction,MarkAsSpamBulkMail

How do you see the BCL of a message?

Open the message headers and find X-Microsoft-Antispam. Microsoft documents BCL as the field that shows the score (Microsoft Learn). If the message got the bulk verdict, X-Forefront-Antispam-Report also contains SRV:BULK and CAT:BULK. Here's an example, shortened and with illustrative values:

X-Forefront-Antispam-Report: CIP:192.0.2.25;CTRY:US;LANG:en;SCL:6;SRV:BULK;
  IPV:NLI;SFV:SPM;CAT:BULK;DIR:INB;
X-Microsoft-Antispam: BCL:7;

Read it like this: the sender has a BCL of 7, which met the default threshold of 7, so the bulk action applied. Don't use the SCL value to judge bulk mail. Microsoft says in cloud organizations it "doesn't determine whether the message is identified as spam."

Paste real headers into our Email Header Analyzer to pick out these fields. Collect the BCL of five or ten newsletters your users want and five they complain about. That small sample tells you more than any default.

How do you test a new threshold before changing it?

Use the bulk senders insight. It shows how much mail was identified as bulk at every BCL from 1 to 9 "for the last 60 days" and lets you simulate a different threshold (Microsoft Learn). It's available in all organizations with cloud mailboxes.

1. Open https://security.microsoft.com/antispam and select the default policy, Anti-spam inbound policy (Default), or a custom policy.
2. In the details flyout, select Edit spam threshold and properties at the bottom of the Bulk email threshold & spam properties section.
3. Move the slider. The insight shows how many fewer or more messages would be delivered, and how many detections are likely false positives or false negatives.
4. For per-sender detail, select View bulk senders insight, or go straight to https://security.microsoft.com/senderinsights.
5. Set New bulk email threshold and Simulation sender quality threshold, then select Simulate.
6. Filter the sender table by New sender blocked, Potential false positive or Potential false negative, and select a sender to see how users treated its mail.

The sender details include how many messages users moved from Junk Email to Inbox and back, how many they deleted, and whether a Tenant Allow/Block List entry allowed or blocked the sender. Use Export to save the list as CSV for the record.

One caution: Microsoft says simulation "might not work correctly if the MX record for your Microsoft 365 domain points to a non-Microsoft service or device." You can also see bulk volume by BCL in the Threat protection status report with the Bulk complaint level slider.

How do you change the bulk email threshold?

In the portal:

1. Go to Email & collaboration > Policies & rules > Threat policies > Anti-spam.
2. Select the default or a custom inbound policy.
3. Select Edit spam threshold and properties.
4. Set the Bulk email threshold slider and save.
5. Under Actions, confirm what Bulk compliant level (BCL) met or exceeded does: Junk Email, quarantine with a quarantine policy, or another action.

In Exchange Online PowerShell:

Set-HostedContentFilterPolicy -Identity Default -BulkThreshold 6 -BulkSpamAction MoveToJmf

BulkThreshold accepts 1 to 9. BulkSpamAction accepts MoveToJmf (the default), Quarantine, AddXHeader, ModifySubject, Redirect, Delete and NoAction. Avoid Delete, which Microsoft warns can't be undone.

Why your change may do nothing

If users are covered by the Standard or Strict preset, settings in the default and custom anti-spam policies "are ignored" for them. You can't change the preset thresholds of 6 and 5. To use another value, exclude those users from the preset and create a custom policy, as described in preset security policies in Microsoft 365. Our anti-spam policy guide covers the other settings on the same pages.

How do you give one team a stricter threshold?

Create a custom anti-spam policy for that group. In PowerShell it's a policy plus a rule (Microsoft Learn):

New-HostedContentFilterPolicy -Name "Finance bulk 5" -BulkThreshold 5 `
  -BulkSpamAction Quarantine

New-HostedContentFilterRule -Name "Finance bulk 5" `
  -HostedContentFilterPolicy "Finance bulk 5" -SentToMemberOf "Finance" -Priority 0

Custom policies run in priority order before the default policy, and protection "stops for a recipient after the first policy is applied." Recreate any other settings the group had, such as spam actions and quarantine policies, because a new policy starts with Microsoft's default values (a bulk threshold of 7, for example), not with the values you changed in your default policy. Microsoft gives the same advice when it describes moving users to a new policy.

Which threshold should you choose?

There's no universal number. Use this as a starting point:

Microsoft's own guidance points the same way. It recommends a minimum value of 5 even for users who opt in to the Promotions folder, and the Standard and Strict values are 6 and 5. If the problem is clutter rather than risk, the Bulk moves enabled setting, still labelled a preview on Microsoft's policy pages and, according to Microsoft, rolling out to all organizations by the end of October 2026, can deliver promotional bulk mail below the threshold to a Promotions folder instead. The graymail guide explains that option.

What if a wanted sender is above the threshold?

Don't raise the threshold for the whole company to rescue one newsletter. Use the narrowest fix:

1. Check the headers. Confirm the verdict was bulk (CAT:BULK) and not spam or phishing. If it was spam, see why Microsoft 365 sends email to junk.
2. Let the user decide. A user who adds the sender to Safe Senders in Outlook gets that mail in the inbox.
3. Add an allow entry for the organization. A Tenant Allow/Block List allow entry can override the bulk verdict directly. Microsoft lists bulk among the verdicts a direct allow entry overrides (Microsoft Learn). It's removed 45 days after last use by default.
4. Tell the sender. A high BCL means recipients complain about their mail. Only the sender can change that, by mailing people who asked for it and honoring unsubscribes.

If you send newsletters yourself and your mail lands in Junk at other Microsoft 365 organizations, run the Bulk Sender Requirements Checker on your domain.

Next steps

• Run the Get-HostedContentFilterPolicy command above and confirm MarkAsSpamBulkMail is On everywhere.
• Open the bulk senders insight and simulate one step down from your current value before changing it.
• Apply stricter thresholds to high-risk groups through a custom policy rather than to everyone.
• Review spam that still gets through with why spam gets through Microsoft 365.
• If you want one set of filtering rules and a per-user quarantine in front of every mailbox, see how iBlockSpam works with Microsoft 365.

Browse all spam filter setup guides.