I recently realized that all mail traversing my sophos UTM headed outbound to my ISP smarthost was being spooled on my server. After checking into it, I found it was very similar to the issues I had back in September of last year. The same fix didn't seem to apply this time, so I started troubleshooting a little bit.
I bypassed the UTM by allowing my mail client (outlook) to connect directly to my ISP smarthost (smtp.verizon.net) on port 465 outbound. This worked successfully. I then reverted back to the old server that had been working on my UTM from September until yesterday (outgoing.verizon.net) on port 25 outbound. My mail client could not connect. I can establish a SMTP session via telnet from the UTM console, but it appears that verizon is not allowing me to authenticate to the outgoing.verizon.net mail server on port 25 any longer. This server was said to be decommissioned by verizon back in 2009, but it seems they have kept it online and functioning - at least until now.
I'm trying to find out if there is a way to successfully enable SMTP SSL encryption for outbound traffic to a smarthost on the UTM. I see where you can require TLS encryption, but that seems to be the only option.
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