Re: How to use port 465 ?

On Thu, 2025-05-29 at 15:37 -0700, Mike Wright wrote:
> My new ISP blocks port 25 (hard block at network level; no overrides)
> so I have to use 465 instead.  (I've never used port 465 before and
> don't know anything about using it.)  Port 465 in the firewall has
> been opened.  Mail client is Thunderbird.  SMTP settings are  465,
> STARTTLS, no authentication.  Attempt to send mail eventually times
> out with error :+

Port 25 is considered a "server to server" SMTP port, and frequently
blocked for MUA use, especially on public access points, and
increasingly by ISPs.

The appropriate port for MUA (mail user agent) connection these days is
port 587, considered the "mail submission port", as per RFC-4409.

See <https://www.rfc-editor.org/rfc/rfc4409https://www.rfc-editor.org/rfc/rfc4409>

Unlike Port 25, use of port 587 requires authentication from the client
end. Port 587 supports TLS natively and STARTTLS as well.

Use of port 465 by an MUA is deprecated, although still suported in
some cases.

-- 
Lindsay Haisley       | "Never expect the people who caused a 
FMP Computer Services |     problem to solve it."
512-496-7118          |        -- Albert Einstein
http://www.fmp.com    |







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