Apple Mail (macOS) search does not find short alphanumeric strings (e.g. booking references)

Apple Mail (macOS) search does not find short alphanumeric strings (e.g. booking references)

I’ve run into what appears to be a reproducible bug in Apple Mail on macOS and I’m posting here to document it in case others are seeing the same behaviour.

Environment

• macOS 26.2 (Tahoe)
• Apple Mail
• iCloud Mail account
• Apple silicon MacBook Pro

Issue

When searching in Apple Mail using the main search bar, short uppercase alphanumeric strings (for example flight booking references such as DG5DRC) return no results, even though the string clearly appears in the message subject and body.

What works

• Using the toolbar filter: Subject → contains → DG5DRC
• Smart Mailboxes with a rule like “Entire message contains DG5DRC”
• Searching for the same string in:
• 
  
  • Mail on iPhone (iOS)
  • iCloud Mail via the web
  • A third-party macOS mail client (MailMaven)

What does not work

• Typing DG5DRC directly into the Apple Mail search bar (All Mailboxes) on macOS — zero results returned

What I’ve already tried

• Rebuilding Mail Envelope Index
• Resetting MailData
• Rebuilding indexes in Safe Mode
• Letting indexing fully complete
• Full account re-sync

None of the above resolves the issue.

Because the same message is found via subject filters, Smart Mailboxes, iOS Mail, and iCloud Mail (web), this looks like a macOS Apple Mail search-bar parsing/tokenisation issue, rather than an indexing or data corruption problem.

Current workaround

Use Subject contains… or Smart Mailboxes when searching for booking references or similar codes.

Posting here mainly so others can confirm whether they’re seeing the same behaviour.