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On 19/04/13 19:46, Gordon Henderson wrote: > On Fri, 19 Apr 2013, Brad Rogers wrote: > >> On Fri, 19 Apr 2013 17:09:23 +0100 >> Neil Winchurst <barnaby@xxxxxxxxxxxx> wrote: >> >> Hello Neil, >> >>> Meanwhile, just out of interest, is there any significance in which >>> port is set up? I don't really understand what difference it would >> >> Yes. Port 25 is for plain SMTP. Port 587 is for an SSL SMTP >> connection. If you connect on port 587 without using SSL, the send will >> fail. > > That's not quite correct. > > In these enlightened days, port 25 is SMTP - that's for transfering > email between servers. Port 587 is SUBMIT - that's the port you're > supposed to use to submit email to a server to be sent. > > I encourage all my clients to use 587 these days - some ISPs may block > direct outbound on 25 which is a PITA if you're need to send email > without using your ISPs mail server. > > SSL/Encryption can be applied to either port. > > Gordon > And to add to the confusion, certain very large technology companies with huge mail services (*cough* google *cough* yahoo) continue to ignore the standards and do what they feel like, which is why there's a currently roughly 50/50 split between: SMTP SSL/TLS over port 465 SMTP with STARTTLS over port 587 Also, technically there's no reason why port 25 SMTP can't also use encryption, either SSL/TLS or STARTTLS although personally I set up my servers to accept SMTP with STARTTLS on 587 as god intended. Port 587 doesn't *require* encryption either, it's just become the accepted (and sensible) standard practice. Ah, email servers. Still confusing admins after all these years... Regards -- The Mailing List for the Devon & Cornwall LUG http://mailman.dclug.org.uk/listinfo/list FAQ: http://www.dcglug.org.uk/listfaq