SHA1 is depcrecated as of january 1st this year - at least on browsers. I have not switched my ironport certificate yet, and not my intra exchange certificate (the external ones are replaced). Will I get into trouble january 1st on my intra exchange communication that use TLS / SSL and will I get problems with mail TLS negotiations on my Ironport mx?
You will not run into trouble as you probably have noticed. It is advisable however to upgrade your PKI server so that you can start using SHA2 certificates asap.