I have rtfm'd, stff'd and stfw'd & so far no joy. So, either I'm blind, stupid or the only person with this issue (delete as applicable)
My zimbra MTA has TLS auth only set. Everything is working ok but when a client (generally Outlook) connects to send a message I get security warning with regard to the server's certificate (screen shot attached).
If I click yes then everything is ok so it's more of a nuisance really. Have tried importing various server certs on client machine but, as yet, to no avail.
Can anyone tell me how to suppress this irritating popup, I'm getting very snappish with users who phone me to tell me that their mail is not working, only to find that it is just this message.