Since 20:44 yesterday, we have experienced some intermittent POP3 issues on one of our back-end mail servers.
We’re not quite sure what is causing this, and suspect a software issue within the ZFS system.
We have (hopefully) put in some changes that will stop this recurring, but we may need to do an emergency reboot of the system at some point to fix it properly. This will unfortunately affect IMAP and SMTP forwarding users on that server, but shouldn’t take more than 10 minutes or so.
More information will come as and when we know.
Meanwhile, apologies to all those affected by this.