Apple Mail Local Data — Technical Reference

Storage Root

~/Library/Mail/V10/
├── MailData/Envelope Index     ← SQLite, central index of ALL mail across all accounts
└── <UUID>/                     ← one directory per synced account
    └── <Mailbox>.mbox/.../Data/[0/5/1/]Messages/<ROWID>.emlx

Critical: emlx File Location

The Data/ subfolder depth is unpredictable (Data/Messages/, Data/1/Messages/, Data/0/4/1/Messages/, Data/0/5/1/Messages/). Always locate by ROWID using find:

find ~/Library/Mail/V10/ -name "<ROWID>.emlx" 2>/dev/null | head -1

Two emlx variants exist:

• <ROWID>.emlx — full message downloaded (headers + complete body)
• <ROWID>.partial.emlx — IMAP lazy-load: headers + truncated body (Apple Mail downloaded the start but not everything). Body is usually readable; just may cut off near the end.

The shared parser (~/.claude/skills/_mail-shared/parser.py) tries full emlx first, then falls back to partial automatically. Do not treat partial files as "not cached" — read them and extract what body is available.

SQLite Database

DB="$HOME/Library/Mail/V10/MailData/Envelope Index"
sqlite3 "$DB" "..."

Key Tables

Automation & Newsletter Columns (replaces address regex)

automated_conversation:
  0 = unclassified (includes real humans AND some bots — not a clean human flag)
  1 = transactional automated (Jira, Slack notifications — can accept replies)
  2 = bulk automated (newsletters, monitoring, bank notifications, CI/CD, marketing)

unsubscribe_type:
  0   = no unsubscribe header (humans, transactional)
  1   = has List-Unsubscribe RFC header (newsletters, marketing — most reliable)
  2,3,6,7 = other list/subscription header variants
  NULL = not yet classified (treat like 0 for filtering)

Use the right filter for the context:

• "Reply needed from a human" (mail-needs-reply): automated_conversation = 0 AND unsubscribe_type = 0
• "Humans + transactional" (Jira, Slack, bank alerts): automated_conversation IN (0,1) AND unsubscribe_type = 0
• "Anything non-bulk" (action items, digest Tier 1+2): automated_conversation != 2
• "Pure noise" (newsletters, monitoring, CI/CD): automated_conversation = 2 OR unsubscribe_type > 0
• "Newsletter specifically": unsubscribe_type > 0

Note: automated_conversation = 1 includes Jira, Slack notifications — they can be action items but humans don't expect a reply to them. Use = 0 for "needs human reply" contexts.

Fast-Path Stats

• mailboxes.total_count — accurate all-time total per mailbox, no COUNT(*) needed
• mailboxes.unread_count — only accurate for EWS/Exchange; IMAP accounts always 0. Use COUNT(*) WHERE read=0 for IMAP unread.
• messages.summary FK → summaries.summary text — fast body preview without emlx parsing, but only populated for ~5% of messages (mostly last 2-3 days). Use as fast-path when available.

list_id_hash

Numeric hash of the mailing list ID. 39k+ rows populated. Same hash = same mailing list. Use GROUP BY list_id_hash to find distinct mailing lists and their volume.

Date Format

date_received is standard Unix epoch (NOT Apple's 2001 Core Data offset):

datetime(m.date_received, 'unixepoch', 'localtime')
-- Last N hours:
WHERE m.date_received >= (strftime('%s','now') - 3600 * N)
-- Yesterday:
WHERE datetime(m.date_received,'unixepoch','localtime') >= date('now','-1 day')
  AND datetime(m.date_received,'unixepoch','localtime') <  date('now')

Standard Query Template

SELECT datetime(m.date_received,'unixepoch','localtime') as dt,
       s.subject, a.address as sender, a.comment as sender_name,
       mb.url as mailbox, m.ROWID, m.read, m.flagged, m.size
FROM messages m
JOIN subjects  s  ON m.subject = s.ROWID
JOIN addresses a  ON m.sender  = a.ROWID
JOIN mailboxes mb ON m.mailbox = mb.ROWID
WHERE m.deleted = 0
  AND mb.url NOT LIKE '%Spam%'
  AND mb.url NOT LIKE '%Trash%'
  AND mb.url NOT LIKE '%Junk%'
  AND mb.url NOT LIKE '%Draft%'
ORDER BY m.date_received DESC;

Account Type from mailbox URL

• imap://UUID/... → Gmail or IMAP
• ews://UUID/... → Exchange/Outlook (work)
• iCloud: imap with INBOX.mbox structure

Discover All Account UUIDs

ls ~/Library/Mail/V10/ | grep -v MailData

Identify Which UUID = Which Email

SELECT a.address, COUNT(*) as cnt
FROM messages m
JOIN mailboxes mb ON m.mailbox = mb.ROWID
JOIN recipients r ON r.message = m.ROWID
JOIN addresses a ON r.address = a.ROWID
WHERE mb.url LIKE '%UUID_HERE%' AND r.type IN (0,1)
GROUP BY a.address ORDER BY cnt DESC LIMIT 3;

emlx Parsing (Python)

import email, re

def parse_emlx(path):
    with open(path, 'rb') as fh:
        fh.readline()          # skip byte count (emlx-specific)
        content = fh.read()
    msg = email.message_from_bytes(content)
    body = ""
    for part in msg.walk():
        ct = part.get_content_type()
        if ct in ('text/plain', 'text/html'):
            payload = part.get_payload(decode=True)
            if payload:
                b = payload.decode('utf-8', errors='replace')
                if len(b) > len(body):
                    body = b   # prefer the largest part
    # Strip HTML
    body = re.sub(r'<style[^>]*>.*?</style>', ' ', body, flags=re.DOTALL|re.IGNORECASE)
    body = re.sub(r'<[^>]+>', ' ', body)
    body = re.sub(r'&nbsp;', ' ', body)
    body = re.sub(r'&amp;', '&', body)
    body = re.sub(r'&#\d+;', '', body)
    return re.sub(r'\s+', ' ', body).strip()

Noise Filters

Prefer column-based filters over address regex — they are indexed and more accurate:

• automated_conversation = 2 — bulk automated (newsletters, monitoring, CI/CD, bank notifications)
• unsubscribe_type > 0 — newsletter/mailing list (has unsubscribe header)
• Folders to always exclude: Spam, Trash, Junk, Drafts, Sent (via mb.url NOT LIKE '%Spam%' etc.)

For subject-based noise: PROBLEM:, OK:, ALARM:, CRIT: prefixes indicate monitoring alerts.

Note: searchable_messages.message_body_indexed is an INTEGER flag (indexing status), NOT body text. Do not use it for content retrieval.

Shared Parser Script

A reusable parser lives at ~/.claude/skills/_mail-shared/parser.py. Use it with:

python3 ~/.claude/skills/_mail-shared/parser.py <ROWID1> [ROWID2 ...]

Returns JSON array with body text and attachment filenames per ROWID.