It's taken ten days since the ACCU conference, but I finally cleared the nearly 10,000 emails which had backlogged since Dec 1st 2015. Next step is to replace my email server, the current one is running Ubuntu 12.04 LTS installed in May 2012 and considering it is an entirely hand rolled installation, it has served me very well during the last four years, though it has begun to fall over increasingly in the last six months or so (I have hourly cron scripts which resurrect it automatically - most of the time). One particularly irritating failure during the past year is that mail box search died for some reason, and with ~10k emails in your account I had to keep finding everything by hand. That hopefully goes away soon.
The new email server is theoretically ready to go. Rather than invest the two dozen hours required to hand roll a new email server from scratch, I started from Mailinabox (https://mailinabox.email/) which is essentially a pre hand rolled email server from scratch based on Ubuntu 14.04 LTS. I forked his github repo and did quite a bit of customisation, mainly replacing his RSA keys with Elliptic curve ones (as of earlier this month my SSL certs are 100% elliptic and SHA2 based) and tweaking his distro to work inside a LXC container, plus I have regex based email aliases which is very unusual though postfix handles that with ease. I walked through all of his postfix and dovecot config, and generally speaking it's okay with a few minor issues. I'll be exposing only IMAPS and SMTP publicly, so none of that cloudy stuff, webmail stuff nor ActiveSync stuff bundled into Mailinabox all of which will remain secured behind a VPN.
To turn on the new server, I simply remap the ports to the new server. Takes less than sixty seconds. If I've made a horrible mistake, sixty seconds to put it back. Here's hoping it "just works", and that massive personal cloud upgrade I began earlier this year will be finally finished and I can move onto more interesting chores to do.