Some mail clients, don't set the References headers, but Thread-Index.
Is there a way to parse this header in Python?
Related: How does the email header field 'thread-index' work?
Mail 1
Date: Tue, 2 Dec 2014 08:21:00 +0000
Thread-Index: AdAOBz5QJ/JuQSJMQTmSQ8+dVs2IDg==
Mail 2 (Which is related to Mail 1)
Date: Mon, 8 Dec 2014 13:12:13 +0000
Thread-Index: AdAOBz5QJ/JuQSJMQTmSQ8+dVs2IDgE4StZw
Update
I want to be able to link these two mails in my application. It already works perfectly for the well known References and In-Reply-To headers.
Using the info here, I was able to put the following together:
import struct, datetime
def parse_thread_index(index):
s = index.decode('base64')
guid = struct.unpack('>IHHQ', s[6:22])
guid = '{%08X-%04X-%04X-%04X-%12X}' % (guid[0], guid[1], guid[2], (guid[3] >> 48) & 0xFFFF, guid[3] & 0xFFFFFFFFFFFF)
f = struct.unpack('>Q', s[:6] + '\0\0')[0]
ts = [datetime.datetime(1601, 1, 1) + datetime.timedelta(microseconds=f//10)]
for n in range(22, len(s), 5):
f = struct.unpack('>I', s[n:n+4])[0]
ts.append(ts[-1] + datetime.timedelta(microseconds=(f<<18)//10))
return guid, ts
Given a thread index, it returns a tuple (guid, [list of dates]). For your test data, the result is:
> parse_thread_index('AdAOBz5QJ/JuQSJMQTmSQ8+dVs2IDgE4StZw')
('{27F26E41-224C-4139-9243-CF9D56CD880E}', [datetime.datetime(2014, 12, 2, 8, 9, 6, 673459), datetime.datetime(2014, 12, 8, 13, 11, 0, 807475)])
I don't have enough test data at hand, so this code might be buggy. Feel free to let me know.