SMTPS
SMTPS refers to a method for secure communication in e -mail transport via SMTP over SSL / TLS and enables authentication of the communication partners at the transport layer as well as integrity and confidentiality of the transmitted messages. An end-to -end security is thus not achieved, since all mail servers and mail relays process the e- mail in plain text ( must ). A confirmation e- mail at the application level is not accessible through SMTPS.
SMTPS is not a separate protocol, and no extension of SMTP, since it works transparently and independently of that at the transport layer.
This means that the connection is handled by SMTP is by software protected by the method SSL or TLS. This is done directly during connection establishment, before any data is exchanged mail. Thus, since the use of the data link layer is not negotiated, SMTPS services usually on a separate TCP port are accessible.
Originally, the Internet Assigned Numbers Authority had registered for SMTPS port 465 in early 1997. The end of 1998 this was revoked when STARTTLS is specified. With STARTTLS, the same port may be used without TLS and TLS. For SMTP which was considered particularly important because clients are using this protocol also foreign servers from which they can not know if they have a separate port for TLS. On the port 465 Source Specific Multicast for audio and video is now registered.
SMTPS is nevertheless continue to be offered on port 465, but also on port 587 for Message Submission RFC 4409th Since Message Submission but could never enforce far-reaching and in many organizations, the outgoing and / or incoming SMTP port as an anti -SPAM measure is blocked, it can be assumed that port 465 be used in the foreseeable future for client to Server transfers.
Swell
- Internet e -mail protocol