Example :
The user had internet id as abc@abc.com. It has been changed to abc@efg.com.
Now when the user is trying to send an internet mail, her internet id is right to the recepient. But when she is replying to any internet mail, the id gets changed to abc@abc.com to the recepient.
Checked up all Client end settings, All seemed OK. There is no such rule on the SMTP Server Config too.
Any Clue will be helpful.