501 Mail path must not include special characters issue

Recently, our company's MDaemon mail server, to the 186 mailbox send mail times wrong "501 Mail path must not include special characters", see the following detailed log:

The reason is that MDaemon has a "reverse scattering protection" function, after this function, mail hair sender address in front of the add "prvs= ...", causing the other party's mail server system does not recognize, will report this error.

What exactly is "reverse scattering protection"? "Reverse scattering" refers to a response message that a user receives a message that has never been sent. For example, a reverse scattering occurs when a spam message or virus sends a message containing a forged "return path" address. Therefore, when a message is rejected by the recipient server, or if the recipient has an automatic answer or an "out of office"/holiday message associated with the account, the response message will point to the spoofed address. This can result in a huge amount of spoofed post status notifications (DSNs) or automatically answering messages to explode the user's mailbox. Not only that, spammers and virus makers often exploit this phenomenon, sometimes using it to launch denial of service (denial of Service,dos) attacks on mail servers, causing a flood of invalid messages from servers around the world. Most servers in the market now have this feature.

For this workaround: Security---Security settings---Other---add their domain name to the whitelist, or uncheck enable reverse scattering protection.

This article is from the mail server and network Management notes blog, please be sure to keep this source http://19281928.blog.51cto.com/2327194/705913

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