Most recently, the company's mailbox was sent to another company when it always withdrew: Socket connection closed by the other side (how rude!). "Plug: Install MDaemon version is the latest 12.x version, degraded to 10.x version of the normal transceiver." The letter back in the user's mailbox, did not pass over. Check the SMTP out of the log.
From the perspective of log analysis, our server has opened the TSL. Think of this, look at the MDaemon SSL settings, the results found that the 12 version of the default check the SMTP server to use STARTTLS as much as possible. Uncheck the SMTP server to use STARTTLS as much as possible, and immediately send it out.
Attachment: By default, the MDaemon mail server supports the Secure Sockets Layer (SSL)/Transport Layer Security (TLS) protocol for SMTP, POP, and IMAP, as well as Worldclient network servers.
This article is from the mail server and network Management notes blog, please be sure to keep this source http://19281928.blog.51cto.com/2327194/574701
See more highlights of this column: http://www.bianceng.cnhttp://www.bianceng.cn/Servers/Mail/