I've just upgraded to El Capitan (10.11.12) from Snow Leopard (10.6.8). Upgrade seemed to go well until I opened email. email now does not accept my password and shows inactivity due to a port time out issue. IT contact says Macs now do not like pop email accounts, which is what I have. Suggested I close out existing account and switch to imap. My concern is losing old emails in this transition as I refer to them for past business history. Will I lose these emails? If so, is there a way to save these emails and transfer them to the new account?