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We often find ourselves setting up multifunction printers which include to email capability. Until recently virtually all ISPs that we encountered did not force SSL with SMTP. More recently we are finding that many ISPs are now requiring it. As many MFPs don't support SSL with SMTP we find ourselves having to us another SMTP account/provider to handle the sending of email which isn't optimal.

One thought was to host a small SMTP server/relay on premise that would accept email without SSL and relay that using SSL to the ISP's SMTP. Could/would this work? Any other suggestions on getting around this?

The solution would be preferably Windows based; however, anything I could "black box" for the client would also work.

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up vote 2 down vote accepted

One way you could solve this would be with a tool like stunnel. Basically stunnel is a simple TCP proxy that you can accept a non-SSL connection, and then re-transmit the request to something else. It also can work the other way around SSL to non-SSL

A simple mail relay is pretty easy to setup. For example on Debian using Exim as the MTA, the whole thing can be setup simply in the standard package configuration. Set it up to be a satellite system, give it the IP of the upstream provider, and specify the lists of IP addresses/networks that it is permitted to relay for.

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Why bother using the ISP's server at all? If you're going to set up an SMTP relay then just configure it to allow relaying for the clients in question and have it use DNS to send the email to the destination domain.

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