If you were using on-server email then it would have been down as well where as if you were using external email such as Google Apps then it would have still been active (as it would be located on a different physical server). We run clustered DNS so even if the server that hosts your site is offline, your DNS will still work.
With regard to email - do you have any comments or ideas as to how incoming and outgoing were handled during the server downtime and restore. I have personally sent some as a test (from laptop to pc, different addresses) that have not been received. They were held in my outbox until the connection established during or after the restore and then sent. However not received.
I have a couple of clients who are anxious about emails that they should have received during this time - for one, an insurance agent, there is legal ramifications and therefore they need to have a bit more information as to how to address this. I am going to advise them to send out an eblast to their correspondents and ask them to resend all email from Thursday on, however I would like to be able to respond to their queries with some background.
Generally mail servers will queue failed sends for up to 72 hours and the outage was less than a total of 72 hours so most mail that was sent to you or your clients during that period should hit your inbox however there is no guarantee that every sending server is going to queue them for 72, some only do 24 and some don't do it at all.
If there is mail they've missed, it should have hit their inbox by now.