We have application being deploy in development to test send an email in Thai character to customer in internet. This application use production Exchange 2007 SP3 to relay email out.
Recently, I have complain from the application owner saying that when they send a test email to yahoo account, it will show invalid Thai characters. To GMAIL, Hotmail is ok.
I had asked him to a postfix smtp (Unix box) and Exchange 2007 relay (testing environment) to relay email to yahoo, the character show just fine.
The mail flow for:
Exchange Testing env. = Application > Hub > Edge > Internet
Postfix = Application > PostFix SMTP > Internet
Exchange production = Application > Hub >Edge > Symantec Cloud > Internet.
We suspected Symantec cloud issue, logged a case with them but they found no issue.