Many iPhone 17 , 16 Pro max and older iphone, ipad users are reporting a frustrating mail bug after updating to iOS 26.4 where blocked senders are no longer being moved to Trash correctly in Exchange and Microsoft Office 365 accounts.

The issue appears to affect the built-in Apple Mail app on iPhone and seems heavily connected to:

• Exchange mail accounts
• Office 365 accounts
• blocked sender filtering

Before iOS 26.4, the feature reportedly worked normally for many years.

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What Exactly Is Happening?

After updating to iOS 26.4:

• blocked emails still receive the red blocked icon
• Apple Mail recognizes the sender as blocked
• BUT the email remains in Inbox
• “Move to Trash” no longer works properly

Instead of moving blocked messages automatically:

• the emails stay visible in the Inbox
• users must manually delete them

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Devices and Environment Affected

Users report the issue on:

• iPhone 17 Pro
• iPhones running iOS 26.4
• Exchange accounts
• Office 365 mail accounts

The setting:

Settings → Mail → Blocked Sender Options → Move to Trash

is already enabled correctly.

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Why This Is Frustrating

The blocked sender system still partially works because:

• the Mail app correctly identifies blocked senders
• blocked emails get visually flagged

However:

• the client no longer performs the actual “Move to Trash” action

This makes the bug feel like:

• a broken mail rule
• failed mailbox action
• client-to-server sync issue

rather than a completely failed blocking system.

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Troubleshooting Steps Users Already Tried

Affected users report trying nearly every common fix without success.

These include:

Mail Setting Reset

• switching:
  • “Leave in Inbox”
  • back to:
  • “Move to Trash”

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Reblocking Senders

• removing blocked senders
• adding them again

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Force Restart / Hard Reset

• rebooting the iPhone completely

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Waiting for Post-Update Indexing

• allowing over 24 hours for background syncing

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Exchange Mailbox Verification

Checking:

• Deleted Mailbox routing
• Advanced account settings

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Mail Sync Reset

• disabling Mail sync
• re-enabling Exchange accounts

to refresh local cache and server handshake.

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Blocking Full Contact Cards

Some users even:

• created physical contact cards
• blocked the entire contact manually

But:

• emails still stayed in Inbox

even though the blocked icon appeared correctly.

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Possible Cause of the Problem

The issue appears related to:

• iOS 26.4 Mail app behavior
• Exchange / Office 365 synchronization
• blocked sender rule execution

It may involve:

• broken mailbox routing
• failed Exchange handshake
• client-side automation bug

The system:

• identifies blocked senders
• but fails to trigger the server-side move action

This strongly suggests:

• a Mail app regression introduced in iOS 26.4

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Why Exchange and Office 365 May Be More Affected

Exchange and Office 365 use:

• server synchronization
• enterprise mailbox rules
• advanced mail handling

compared to simpler IMAP accounts.

This means:

• blocked sender actions may require successful server confirmation
• which could now be failing after the update

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Temporary Workarounds

Currently, there does not appear to be a confirmed permanent fix.

However, some users are trying:

• Outlook app instead of Apple Mail
• server-side junk rules in Office 365
• Exchange spam filtering rules
• manual mailbox rules through Outlook Web

These may bypass the broken iOS Mail handling temporarily.

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Is Apple Aware of the Issue?

At the moment:

• many users report the bug
• but no official Apple support article or patch announcement has appeared yet

Because the issue started immediately after iOS 26.4 for many users, it strongly points to:

• a software regression
• Mail app compatibility issue

rather than user configuration problems.

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Final Thoughts

The iOS 26.4 blocked sender bug is causing Apple Mail to:

• recognize blocked senders visually
• but fail to move those emails to Trash

The issue appears especially severe on:

• Exchange accounts
• Office 365 accounts
• enterprise mail systems

Users have already tried:

• reblocking senders
• resetting sync
• force restarting
• recreating contacts
• toggling Mail settings