There looks to be a false positive with the FORGED_MUA_MOZILLA rule when sending form Yahoo as shown by the following example:
Message-ID: <[email protected]> X-Mailer: WebService/1.1.9272 YahooMailNeo Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/56.0.2924.87 Safari/537.36 It looks like an adjustment needs to be made to this rule to account for this.
