[Oberon] Re (2): Revision of OpenSMTP(...) in Oberon.Mail.Mod.

joerg.straube at iaeth.ch joerg.straube at iaeth.ch
Mon May 1 15:37:21 CEST 2023

>> In RFC3207 (2002) the use of TLS encryption was added to SMTP; to
>> change from TCP to TLS the command STARTTLS was added. RFC8314 (2018)
>> recommends the use of „Implicit TLS“ iso STARTTLS.
> Apology for my uncertainty and confusion.  By "iso" do you mean
> "equivalent to"?  "Contrasting to"?
iso = instead of = contrasting to

> Over years, "official" meanings and recommendations have changed.
> https://en.wikipedia.org/wiki/List_of_TCP_and_UDP_port_numbers
> Ref. 465 and 587.

Indeed, the history of the SMTP ports is a little confusing. Basically, in today‘s world it is strongly recommended to use SMTP with encryption. As POP and IMAP use dedicated ports for implicit TLS, SMTP should do the same.
Therefore, in the long run
465 = SMTP over TLS should be the goal
587 = SMTP over TCP with change to TLS via STARTTLS was a kind of quick add-on in 2002 to add encryption to SMTP.

1) 465 implicit TLS
2) 587 with STARTTLS
3) 587 without STARTTLS

> Guenter Feldmann begin work on SSL in ETH Oberon more than a decade
> ago.  I recall using scp.  Also Guenther added SSH in A2 years ago?  I
> don't know the current status in A2.

A decade ago, we had TLS 1.2 (RFC5246, 2008). Today, we are at TLS 1.3 (RFC8446, 2018)
Most probably, some of Guenter‘s good work must be adapted.

> Another possibility is a TLS tunnel, as available by stunnel in Linux.

Yes, if you are not native but run Oberon OS on top of another OS, you can use the TLS functionality of the underlying OS.

> Therefore, I think of the analogue for SMTP.  Add AUTH PLAIN in
> Oberon.Mail.OpenSMTP.

Authenticating a user with a password to the mail server is independent of the underlying transport encryption with TLS.


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