Suddenly, today, when I reply to an email OR start a new email - as soon as I start typing nothing happens and a couple of seconds later EM crashes and closes.
FYI, using Windows 10 on a laptop. EM Client is set up with an imap account.
Any help would be greatly appreciated.
Backup from within eMC
You could remove the account and re-add the account
You could uninstall eMC, do not delete database, and reinstall with current version from here
If removing and re-adding the account or uninstalling and reinstalling the program makes no difference as @sunriseal advised above, this would then normally indicate something else in memory running in the background on the computer interfering with eM Client.
Common program running resident that can cause this type of thing are eg: Optional Antivirus scanning program, Firewalls, Security programs, VPNs etc. So if you have any of these type of “Optional programs” installed or recently updated, suggest to try disabling them temporarily to test if they are the cause of the issue.