* Jean-François Bachelet: >> Many ISPs do not allow outbound connections to port 25. That is a >> fairly standard configuration to block spam from the ISP's customers. > > I know this, it's exactly why I want my out mail to use only secure > ports 465 and/or 587.
Many remote MX hosts do not offer ports 465 and/or 587 at all, and those hosts that do usually enforce authentication for message submission on these ports. Every reasonably configured MX expects third-party mail to arrive on port 25. If your ISP does indeed block outbound traffic to TCP port 25, you can either use the ISP's SMTP relay servers or switch ISPs. Personally, I do not use hosting services which block outbound traffic on any port. -Ralph
