I have an Dreamhost hosting account which handles all my email, don't use Verizon at all.
For last year or so have used 587 w/ STARTTLS with no issues. Always worked fine.
Suddenly can't connect at all from Verizon. Configuration unchanged on client side, but all attempts to contact that host will timeout. But fire up my VPN to tunnel the traffic and it works fine. And exact same client PC works fine in dozens of other locations / networks with same config.
Can't find anything at all in my router that would indicate an issue. Config unchanged from when it was working fine.
Tried 465 w/ SSL/TLS and same result - works great via tunnel, blocked on Verizon.
Destination SMTP server = a Dreamhost server
587 / STARTTLS fails to connect via Verizon, fine via VPN and same client hardware/config on other networks
465 / SSL/TLS fails to connect via Verizon, fine via VPN and same client hardware/config on other networks
Any suggestions? Has Verizon suddenly blocked a number of hosting companies? Quite irritating to have to fire up the tunnel just because of sending basic emails.
Based on your description of the issue, I wonder if maybe Dreamhost is blocking connections from your IP? Do you know if your IP address has changed recently?
I would recommend getting a new IP address to see if that helps. The simplest way to do this is to turn off your router for a few hours. (Before you go to bed or out to run errands are good times.)
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