Recently started getting this Error message when attempting to view a reply I sent to a message. "Mail was unable to find your reply to the message Re: Barns. You may have deleted the message." The reply is in the Sent box of the correct account. It had been working. Don't know if it started with the 10.7.4 update. I also have moved to GMail accounts. Three GMail POP accounts, none are able to find the replies. Set to remove message from server after one month and Delete Sent/Trash after one month. Two are linked to my ISP email accounts which I have deactivated in Mail. Doesn't seem this should be a factor but I used Time Machine to recover an old message. After the restore, one of my accounts reverted to the settings for an old RoadRunner I no longer have listed but retained the GMail icon in the accounts list. Odd. Thanks for any light you might shed on this little problem. Doug.