SMTPS
method for securing SMTP with transport layer security
SMTPS (Simple Mail Transfer Protocol Secure) is a method for securing the SMTP using transport layer security. It is intended to provide authentication of the communication partners, as well as data integrity and confidentiality.
SMTPS is neither a proprietary protocol nor an extension of SMTP. It is a way to secure SMTP at the transport layer, by wrapping SMTP inside Transport Layer Security (TLS). Conceptually, it is similar to how HTTPS wraps HTTP inside TLS.
This means that the client and server speak normal SMTP at the application layer, but the connection is secured by SSL or TLS. This happens when the TCP connection is established, before any mail data has been exchanged. Since whether or not to use SSL or TLS is not explicitly negotiated by the peers, services that speak SMTPS are usually reachable on a dedicated port of their own.
Difference between SMTPS and smtps
"smtps" is also the name of an IANA-registered service, with the TCP port number 465. The service was intended for use by Mail Transfer Agents (MTAs), as a point of contact where these could exchange email in an encrypted form rather than in plaintext. The registration was quickly revoked, however, as standardization efforts resulted in an alternate approach. The registration has never been reinstated.
When describing the IANA service registration, the official capitalization is "smtps".
This brief starts where responsible research should: with the source description of “SMTPS” as method for securing SMTP with transport layer security. Everything that follows is an evidence route, not borrowed authority.
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The subject matters to the general reference register because the source frames it as method for securing SMTP with transport layer security. Its deeper value depends on whether names, dates, institutions and citations support that framing.
The citation trail is more important than the brevity of the summary: it shows where individual claims can be examined in context. The source revision retrieved here is dated Aug 26, 2026. The linked authority identifier is Q949493. None of the 0 selected statements returned an explicit reference.
Overview language is designed for orientation and should not be treated as a substitute for the evidence cited beneath it. The source lead contains qualifying language; that uncertainty should survive quotation, summary and reuse. Authority statements aid reconciliation but still require their own references, qualifiers and ranks to be checked.
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This entry incorporates text from “SMTPS” on English Wikipedia. Contributors are listed in the page history. Text is available under the Creative Commons Attribution-ShareAlike 4.0 License. Selected authority identifiers and statements are retrieved from Wikidata under CC0; their references and qualifiers remain part of the verification path.