ISP port blocking practice

Fri Oct 23 01:41:25 UTC 2009

Justin Shore wrote:
>  The vast majority, I'm 
> sorry to say, used Microsoft Exchange which to the best of my knowledge 
> doesn't support RFC2476.  

You can configure exchange to use additional smtp virtual servers and 
bind them to specific ports. You can also require authentication to 
access the ports and you can restrict it to users. You can also enable 
it for STARTTLS.

What I dont know is whether Exchange has or ever will support SMTPS 
which is strange considering many versions of outlook default to try 
that for any secured port other than 25.

> I wish more people would use it though.  My users wouldn't have cause to 
> get so upset when I tell them that they have to pay monthly for a static 
> IP to use tcp/25.  It would reduce my hassles a wee bit.

I have many a time recommended consulting customers to follow up with 
their mail provider to see if they has any plans to support the rfc 
standard, but I dont share much enthusiasm for complete adoption. I do 
believe it is getting better.

> 
> Justin
> 
> 