When an estimate is accepted it sends out an email notification to the email address that has been supplied in the routine emails section.
Account Settings > Routine emails
Check the address that you have set up for the default, you may even find that the email has ended up in your junk folder? I would suggest, if this has happened, to add the email address to your contacts/white list the email so that it comes through to your inbox in future.
I created a dummy client with my personal email address and create test transactions a couple of times a year just to make sure that emails aren’t getting zapped by the main spam filters. These are frequently updated and what worked last year may be thought suspicious now.
It’s a good idea to keep checking, it is hard to keep up with the Spam filter changes, but if you white list the email address this should avoid it being caught by Spam