POP3S – a free email transport supporting TLS

Shoobie, doobie do wop – DON’T infiltrate it.

Alexander Ausserstorfer has released a free mail transport agent, POP3S, which performs email fetches using TLS on port 995.

TLS, or Transport Layer Security, is a protocol first introduced at the very end of the 1990s and based on the SSL (Secure Sockets Layer) specification originally developed by NetScape. The aim of the protocol is to allow client-server applications to communicate securely across a network – with POP3S being the client application in this case.

In his announcement, Alexander describes POP3S as a very early developer release – a fact that is reflected in its user interface which, in the discussion following its release on the usenet group comp.sys.acorn.apps1, one user described as “not exactly user friendly” – but that same discussion also brought to light some technical issues which Alexander has promptly investigated and attempted to address; the version currently available for download isn’t the same version that was announced on 24th May.

As well as investigating and addressing problems, the developer has also added more facilities to the program – with the most recent version, released on 30th May, supporting StartTLS (a method by which the client and server can initially communicate using plain text, and upgrade the connection to a secure one), checking server certificates (X.509 standard) and allowing users to skip messages over a certain size.

Alexander asserted in his original announcement that POP3S is the only free mail transport for RISC OS to support TLS – but AntiSpam can also do this. However, POP3S is written in C and compiled with GCC, and uses GnuTLS, which looks to be under active development, to provide the security layer, whereas AntiSpam requires the SecureSockets module from R-Comp, which hasn’t been updated in a number of years and may, therefore, be subject to a number of potential vulnerabilities – and on top of that, the download link for the module does not currently appear to work. All things considered, therefore, while Alexander’s assertion may have been technically incorrect, the unavailability of R-Comp’s module, and the fact that it is several years old anyway, that assertion may as well hold true. POP3S is certainly likely to be the more secure option of the two, anyway.

POP3S can be downloaded from Alexander’s website, with this page about the software being given in the announcement – but while he says that both the application and source code can be downloaded from there, the zip file doesn’t appear to be linked. Luckily, therefore, Alexander has also provided a direct link to the zip file containing the application itself.

Note: Although it does not need to be running, POPStar is also needed alongside POP3S. This is because the latter currently places the downloaded emails in the locations pointed to by POPStar, which are themselves optionally used by email clients on RISC OS to debatch those emails.


  1. That same usenet discussion, as is often the case, quickly veered off-topic and went on to discuss Alexander’s nationality. According to his website, he grew up on the edge of the Bavarian Alps and then spent several years abroad, but he now lives in the Chiemgau Alps in South East Germany – Bavaria once again – somewhere between Munich and Salzburg, just over the border in Austria. He is also a keen cyclist, with a page on his site discussing this, and the distances he covers each year. RISCOSitory is keen on silly nicknames and references, although there aren’t very many – yet – in current use. This background, however, leads easily to a suitable nickname for Alexander, who will henceforth be known on RISCOSitory as “Bicycling Bavarian Alexander Ausserstorfer”. Alliteration, too. That’s always nice.

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