[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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