The certificates issue is a major headache that precludes upgrade to Jessie for the following reasons:
It's far simpler to input domainname.com than the host's FQDN for incoming and outgoing mailbox settings.
Scheduled renewal of Letsencrypt certificates will cause mail delivery issues especially for clients using iOS 10. I currently have 150+ iPhone users sending/ receiving mail via Wheezy, their mail settings include the domain name for incoming/ outgoing, so having them switch to the FQDN would be painful. Likewise upgrading from Wheezy to Jessie would be disastrous.
Domains can't be transferred to another host as smoothly.
Given the importance of email to my clients I need a system that's a bit more robust than Jessie and moreover a system that works with multiple domains, mailboxes and certificates. Wheezy has served us well and appears to work fine with iOS 10 - however it appears that Apple has removed (or hidden) the ability to trust SSL certificates that are self-signed nor does it trust Letsencrypt certificates unless the mail settings include the FQDN.
Sure I’d like to take advantage of Jessie’s bells and whistles but upgrading's not an option.
What really cracks me is that there's no warning of the upgrade mail problems within the Jessie docs nor is there any mention of the Clam Logs disc space consumption issue.
So I’m stuck with Wheezy because it’s brilliant and seems to just work. I’m hoping Bytemark can iron out these issues as part of the Symbiosis Stretch rollout otherwise (sadly) I’ll be forced to migrate to another host.
Kind regards Pete