[CentOS] postfix pb with mass emails

[Feizhou]

> Finally, I'm not so sure about the email being resent because of 
> unreachable recipients.
> One thing I remember:
> In the postfix spool, in the defered dir, there were LOT of emails 
> with different hash names.
> Looking in some of them, I noticed recipients duplicated in several of 
> them, this should not be normal...
> In the logs, I could see some these hashed defered emails being 
> repeated several times, each time with a cause why the mail was being 
> defered.
>
If recipients are duplicated in several different messages, then there 
were multiple injects to the same recipients. Again, as many have 
requested, logs are necessary to look into this issue.