May. 8th, 2016

fanf: (dotat)

I mentioned obliquely on Twitter that I am no longer responsible for email at Cambridge. This surprised a number of people so I realised I should do a proper update for my non-Cambridge friends.

Since Chris Thompson retired at the end of September 2014, I have been the University's hostmaster. I had been part of the hostmaster team for a few years before then, but now I am the person chiefly responsible. I am assisted by my colleagues in the Network Systems team.

Because of my increased DNS responsibilities, I was spending a lot less time on email. This was fine from my point of view - I had been doing it for about 13 years, which frankly is more than enough.

Also, during the second half of 2015, our department reorganization at long last managed to reach down from rarefied levels of management and started to affect the technical staff.

The result is that at the start of 2016 I moved into the Network Systems team. We are mainly responsible for the backbone and data centre network switches and routers, plus a few managed institution networks. (Most departments and colleges manage their own switches.) There are various support functions like DHCP, RADIUS, and now DNS, and web interfaces to some of these functions.

My long-time fellow postmaster David Carter continues to be responsible for Hermes and has moved into a new team that includes the Exchange admins. There will be more Exchange in our future; it remains to be decided what will happen to Hermes.

So my personal mail is no longer a dodgy test domain and reconfiguration canary on Hermes. Instead I am using Fastmail which has been hosting our family domain for a few years.

fanf: (dotat)

This took me hours to debug yesterday so I thought an article would be a good idea.

The vexation

My phone was sending email notifications for events in our shared calendar.

Some of my Macs were trying and failing to send similar email notifications. (Mac OS Mail knows about some of my accounts but it doesn't know the passwords because I don't entirely trust the keychain.)

The confusion

There is no user interface for email notifications in Apple's calendar apps.

  • They do not allow you to create events with email notifications.
  • They do not show the fact that an event (created by another client) has an email notification configured.
  • They do not have a preferences setting to control email notifications.

The escalation

It seems that if you have a shared calendar containing an event with an email notification, each of your Apple devices which have this calendar will separately try to send their own duplicate copy of the notification email.

(I dread to think what would happen in an office environment!)

The explanation

I couldn't get a CalDAV client to talk to Fastmail's CalDAV service in a useful way. I managed to work out what was going on by exporting a .ics file and looking at the contents.

The VEVENT clause saying ACTION:EMAIL was immediately obvious towards the end of the file.

The solution

Sadly I don't know of a way to stop them from doing this other than to avoid using email notification on calendar events.

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