xorsearch.py: Ad Hoc YARA Rules
Adhoc YARA rules allow for easy searches using command line arguments without having to write complete YARA rules for simple use cases like string and regex searches
https://isc.sans.edu/diary/xorsearch.py%3A%20%22Ad%20Hoc%20YARA%20Rules%22/31856
Google Spoofed via DKIM Replay Attack
DKIM replay attacks are a known issue where the attacker re-uses a prior DKIM signature. This will work as long as the headers signed by the signature are unchanged. Recently, this attack has been successful against Google.
https://easydmarc.com/blog/google-spoofed-via-dkim-replay-attack-a-technical-breakdown/
SSL.com E-Mail Validation Bug
SSL.com did not properly verify which domain a particular email address is authorized to receive certificates for. This could have been exploited against webmail providers.
https://bugzilla.mozilla.org/show_bug.cgi?id=1961406