Hi Allen Wang ,
Thanks a lot for your response.
Which version are you used? Is this issue arise after install update for Exchange server?
We are using exchange 2013 sp1 Ent edition.This issue is been existing in my environment when we start to use exchange 2013 and it is not from sp1 .
Also, what your means of second time, server retry to send or send failed then user click to resend?
When an user send an email for the first time to some of the recipient's it is reaching only to the few recipient's mailboxes and the email to the remaining recipients gets failed with the event ID "SUBMITFAIL" on the message tracking log.
Same time if we forward that same message to the failed recipients it went and delivered successfully.
Note : Apart from message tracking log i didn't found anything helpful in protocol and event viewer logs.
Below link is for your Reference :
https://social.technet.microsoft.com/Forums/fr-FR/ae61d80c-58da-4f47-b83c-66b123b2faf4/exchange-2013-mailflow-and-the-hosts-file?forum=exchangesvrgeneral
Above is the link which is saying that this issue will be resolved in exchange 2013 sp1 and also it says it an bug in exchange 2013 CU3 .But still on my end the problems occurs in exchange 2013 CU3 as well as in exchange 2013 SP1.
Please help me out yaar this issue is raising in my production environment.