I made a backup a few days ago, have a new computer, now am concerned that if I restore from the backup, it wipes out the mail that has recently synced with eclient. Should I proceed with the restore?
If you are using POP3 you will lose at least some of your recent data. What you need to do is export anything new since the last backup, (don’t forget the Sent folder) then after the restore you can import it back into eM Client.
If your email account is setup as IMAP it is unlikely that you will lose any synced data because once you have done the restore, all your synced data from the eM Client backup will be replaced by what is on the server. This means all your settings, templates, Rules and local data will now be there from the restore, but your IMAP folders will revert to what is currently on the server regardless of what was in the backup.
It is safe to try restoring with an IMAP account by first making a backup so you can always restore that if restoring the days old back fails. Then restore your previous backup, wait for the sync to complete and see the result. If you are missing recent messages, restore the backup you just made, and do the same for POP3 above.