Messages being deleted rather than stored in Trash
I needed to refer today to an email I deleted around three weeks ago. When I looked in the Trash mailbox, there were only about 10 days' worth of emails in there – the rest had been automatically deleted DESPITE the mailbox being set never to permanently erase Sent, Junk or Deleted items. This is really scary; I carefully set my system up so that I couldn't lose anything even if accidentally deleted, and I now have no record of an email that unexpectedly turns out to be crucially important. Does anyone know why this is happening and how I can stop it? It's an IMAP system; this was the default setting when I first set up my Mac, and left it as that because I had no idea it would turn out to be so hideously unreliable! Thanks for any help you can give.