Hello, I’m on Ubuntu 12.04 X64 on 1GB Ram Droplet also I’ve Zpanel as CP. Some emails are failling to be delivered. I always get same messages for same sent email domains: “Undelivered Mail Returned to Sender” and “Delayed Mail (still being retried)” I made some pastebin for both messages. Here: http://pastebin.com/sv8bdpQg and http://pastebin.com/5AeCFNRj
I don’t know how to fix it.
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