Lost Email

[JLVolk]

It appears that about a year's worth of emails have gone missing from my email account.  Somehow email from early March of 2016 to early April 2017, just seem to have disappeared. We use an iMac computer, with Outlook as our mail server, and we use Time Machine for Back up, automatically.  However, NONE, of our Outlook Identities that have been backed up between these dates - have these missing emails.  This sounds beyond bizarre to me, but I have no explanation.  So, a question is:  is it possible that Verizon might have a record copy of our email file between those dates?  Some of these are very important family business information.  Any advice is welcome.