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Exchange - Extracting Sent Recipients via Graph API

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Extracting Sent Recipients via Graph API

Extract a deduplicated list of every address a mailbox has ever emailed, with the date they were first contacted. Uses Microsoft Graph API via Python to pull directly from Exchange Online.

Prerequisites

  • Access to Azure Portal (portal.azure.com) as an admin
  • Python installed on the machine running the script
  • Python packages: requests, msal — install with: 
    pip install requests msal

Step 1 — Azure App Registration

  1. Go to Azure Portal → Azure Active Directory → App registrations → New registration
  2. Give it a name (e.g. MailExport), leave everything else default, click Register
  3. From the app overview page, note down:
    • Application (client) ID
    • Directory (tenant) ID
  4. Go to Certificates & secrets → New client secret → set an expiry → click Add
    • Copy the secret Value immediately — it won’t show again
  5. Go to API permissions → Add a permission → Microsoft Graph → Application permissions
  6. Search for and add Mail.Read
  7. Click Grant admin consent

Step 2 — The Script

Script: get_sent_recipients.py

Fill in the following at the top of the script:

CLIENT_ID     = "your-client-id"
TENANT_ID     = "your-tenant-id"
CLIENT_SECRET = "your-secret"
MAILBOX       = "[email protected]"

Run it from a terminal (not by double-clicking — the window will close before you see output):

cd C:\path\to\script
python get_sent_recipients.py

Output

A CSV file named unique_recipients.csv in the same folder as the script, with two columns:

email_addressfirst_emailed
[email protected]2019-03-15

Notes

  • Script pages through Sent Items at 999 messages per page — handles large mailboxes fine
  • Handles rate limiting automatically (respects Retry-After headers)
  • Extracts To and CC recipients only — BCC is not stored in message metadata after sending
  • Dates are based on sentDateTime from the Graph API — reflects when the email was sent, not received

Cleanup

Once the extraction is done, remove the app registration or revoke the Mail.Read permission in Azure — no point leaving mailbox read access open indefinitely.

Azure Portal → App registrations → select the app → Delete (or remove the API permission)

  • mailexport — Bayside Letterbox specific run (client IDs, secret, status)

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