550 dkim encountered the following problem validating
Ensure that you do not try to route outbound or journal messages to Mimecast from an IP address that has not been authorized to do so.By default, the Mimecast platform only accepts 100 RCPT TO entries per message body (DATA).Anybody who sends email has seen them, in one form or another – those SMTP error codes, often returned in bounced email, such as “550 Requested action not taken: mailbox unavailable” or “550 5 2 1 mail from refused spam site.” These are often in response to SMTP commands that have ‘gone wrong’ between your email server that sent the email, and the receiving email server that is unable to deliver it (or refuses to deliver it) for some reason. Unfortunately, many receiving systems seem to mix and match these error messages, rather than adhering to the prescribed code messages. (‘SMTP’ stands for Simple Mail Transfer Protocol.) First, here is a list of SMTP codes and error codes, and what each message is supposed to say and mean: 211 – A system status message. (on their side) 452 – The command has been aborted because the server has insufficient system storage.
DKIM, or Domain Keys Identified Mail, is an email authentication method designed to detect email spoofing by providing a mechanism to allow receiving mail exchangers to check that incoming mail from a domain is authorized by that domain's administrators.
When troubleshooting dropped or failed SMTP conversations, there are two main types of codes used; 400 and 500 error codes.
The first number in this code, generally indicates whether the MTA accepted the command or if the command was rejected.
This can also be caused by Firewall issues on the sender's side, or incorrectly configured content rules on a security device.
This error indicates that both the sender AND the recipient email domains specified in the transmission are external to the Mimecast service and therefore are not allowed to relay through the Mimecast service and / or the connecting IP address was not recognized as authorized.If you are trying to send an email to a Mimecast customer and receiving any of the error codes below, this should be escalated to the Mimecast Administrator of the intended recipient.