What is .GRP file extension?
File created by SmarterMail, an email server application used to host Web email access; stores one day's worth of email messages for a mailbox folder; used for storing a database of email messages for a particular user.
GRP files are created with filenames that reflect the date of the email messages. For example, the file 2011-01-01.grp contains all email message data for January 1, 2011 for a particular mailbox folder. GRP files are saved with a corresponding ".cfg" file, which has the list of all email messages and the GRP file where each message is located.
You can see a list of software programs here on easyfileopener.org that can open this file type so that you don’t need to search for it on the web. You can then open your file with this extension using a software listed below.