[RndTbl] Shaw now blocking SMTP port 25
Gilbert E. Detillieux
gedetil at cs.umanitoba.ca
Wed May 23 12:16:45 CDT 2007
On 2007-05-23 11:41, Kevin McGregor wrote:
> Well... yeah. Note that you can still do outbound SMTP if the
> destination SMTP server supports SSL/STARTTLS, such as smtp.gmail.com does:
> Outgoing Mail (SMTP) Server - requires TLS: smtp.gmail.com (use authentication)
> Use Authentication: Yes
> Use STARTTLS: Yes (some clients call this SSL)
> Port: 465 or 587
Actually, there is a difference between TLS (or STARTTLS) and SSL. With
SSL, encryption is enabled (or at least negotiated) right from the
initial connection. An alternative port number is typically used for
this reason. With TLS, the connection starts off in plain text, and
encryption is (optionally) negotiated later, provided both sides support
it. An alternative port number is usually not necessary for this.
Of course, if the whole point is to get around blocking of port 25, then
an alternative port will be required, whether TLS or SSL is used.
> So, it's not ideal as this won't be a solution which can be used by
> everyone affected, but at least it's something.
The problem with this is there isn't a clear standard for alternative
ports for SMTP. So, you need to find out if your particular mail
service supports it, and if so, on what port (and with what encryption
options). Of course, if a standard (even de facto) were to emerge, it
might just shift the spam problem to the other port, unless it only
supports authenticated connections (which, I believe, required TLS
support, not just SSL).
Gilbert E. Detillieux E-mail: <gedetil at muug.mb.ca>
Manitoba UNIX User Group Web: http://www.muug.mb.ca/
PO Box 130 St-Boniface Phone: (204)474-8161
Winnipeg MB CANADA R2H 3B4 Fax: (204)474-7609
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