autoreg-skills-max/skills/github-oauth-automation/references/imap-jwt-extraction.md

IMAP Quoted-Printable JWT Token Extraction

Problem

Verification emails often contain JWT tokens in URLs that are split across multiple lines due to quoted-printable encoding. The = at end of line is a soft break.

Example

Raw email content:

token=[REDACTED]
eyJlbWFpbCI6Im...\r\n
3ODQ3NDM1Mzd9.qiOoGUNZZsPse1jQnZ8JHvUrb6xKX5KbPatfwvXUPGA&callbackURL=3D%2F

Extraction Code

import imaplib, re

M = imaplib.IMAP4_SSL('imap.gmail.com')
M.login(email, app_password)
M.select('INBOX')
typ, data = M.search(None, 'FROM', 'sender')
ids = data[0].split() if data[0] else []
typ, msg = M.fetch(ids[-1], '(RFC822)')
raw = msg[0][1]

# Find token= in raw bytes
idx = raw.find(b'token=')
chunk = raw[idx+6:idx+250]  # skip 'token='

# Remove soft breaks (=\r\n)
result = []
i = 0
while i < len(chunk):
    if chunk[i:i+1] == b'&':
        break
    if i+2 < len(chunk) and chunk[i:i+3] == b'=\r\n':
        i += 3  # skip soft break
    elif i+1 < len(chunk) and chunk[i:i+1] == b'=' and chunk[i+1:i+2] == b'\r':
        i += 3
    else:
        result.append(chr(chunk[i]))
        i += 1

token = ''.join(result)
# Remove 3D prefix if present (= in quoted-printable)
if token.startswith('3D'):
    token = [REDACTED]]

Important

• Python's repr() truncates long strings with ... — the actual string is complete
• The 3D prefix is the quoted-printable encoding of =
• Always work with raw bytes, not decoded text, to avoid encoding issues
• Use b'...' byte strings for searching in raw email content