Closing this out with the expectation we'll work direct with you. Can you write oxidation states with negative Roman numerals? Possible values are: not_initiated, relaxed, moderate, aggressive, cluster, whitelisted_cluster or outbound, Remote IP address of the sending platform, Recipient address prior to message processing, Indicates if the rejection is due to a managed sender entry, Numerical spam score. You need to contact them, only they can tell you why. But, I advised our user to not send a bulk email instead start with low volume of email and increase it gradually. Browse other questions tagged, Start here for a quick overview of the site, Detailed answers to any questions you might have, Discuss the workings and policies of this site. Perhaps suggesting these may be generated due to an unlicensed user still being included on an internal distribution list? By accepting all cookies, you agree to our use of cookies to deliver and maintain our services and site, improve the quality of Reddit, personalize Reddit content and advertising, and measure the effectiveness of advertising. The other odd thing to mention in regards to our current Mimecast configuration - we are only configured for Outbound at the moment. New comments cannot be posted and votes cannot be cast. How do I align things in the following tabular environment? Lately my users are getting bounce backs from mimecast with error code 554 Email rejected due to security policies A signature was detected, which could either be a virus signature, or a spam score over the maximum threshold. Mimecast's solution enables administrators to quickly recover email, calendar, contacts and personal folders by leveraging data in the Mimecast Cloud Archive. I keep on searching on google how to check if some info on our header is missing. Example, we use Mimecast and we reject anything that isn't a valid address. I asked what info they can received on our header, they've sent me this. 1) after the helo, when it only knows source ip, target address and supposed sender. When that particular email tries to be redelivered from the same server, it should be accepted, and that specific triplet gets written to a temporary whitelist. To use this endpoint you send a POST request to: The following request headers must be included in your request: The current date and time in the following format, for example. See here for a complete list of exchanges and delays. Thoma Bravo, a private equity firm which took Proofpoint private in a $12.3 billion deal last April, did not respond to a request for comment. "After considering all the alternatives available to Mimecast, the Board of Directors determined that the Permira transaction is in the best interests of shareholders and the Company," a spokesperson for Mimecast said in a statement. Institutional investor BlackRock owns 7 percent of Mimecasts outstanding shares; co-founder, Chairman and CEO Peter Bauer owns 5.5 percent of outstanding shares; and co-founder and ex-CTO Neil Murray owns 1.3 percent of outstanding shares. They believed such deal would likely result in a lengthy review by antitrust regulators, and few remedies such as divestitures are available, the people said.