Yup, Cyrus was rock solid for us for years with Thunderbird as the client. We were forced into an Exchange replacement (Scalix) and now Google mail because 'Thunderbird is clunky (read: follows all of the user interface guidelines) and Outlook is cool (read: actually forces overrides on windows standard interface behaviour)' and neither backend is solid. Don't get me started on the huge list of LookOUT! WTFs. I wouldn't trust it for e-mails with my mum. GMail sometimes randomly expunges e-mails because it feels like it. Sometimes when you're actually reading the thing. You can't e-mail yourself.