What I’ve learned about calendar client apps

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May 15, 2017

Over the past year, I've spent a few hundred hours sending calendar invitations, testing calendar clients and how each "consume" calendar invitations (actually land on a person's calendar). For us at 31Events, that is the single most important aspect of what we do - ensure our invitations actually get on the calendar.

You would think it's a trivial subject. We've had integrated calendars as long as we've had email, and other productivity tools. But, the calendar is a bit different than email - and it's much more complicated that just "sending" a message and hoping someone opens and reads it.

Why? For one simple fact - we are dealing with "time" and time is different for each of us. Right now, there are 24 different "times" simultaneously happening (time zones) and depending on that time zone, you could be experiencing a completely different "day" than I am.

That causes problems - especially when you are sending something that is time based - it has a beginning time and an ending time.  So, your calendar has to determine who's time to reference - mine or yours? 

Next, we have a general problem with lots of applications that could "consume" that calendar invitation - there are online services, hosted services, static devices, mobile devices, pushed notifications, etc and so on. And each of those have little quirky things that get in the way.

A couple months ago, we decided to test some of the most popular end calendar clients, just to get a feeling for what worked and what didn't - and here's what we found out, when using 31Events.

1. Microsoft Outlook - regardless of which application used (online or installed), is the best at consuming calendar information. Almost 100% of our tests invitations worked - meaning we received the email notification, and at the same time, the invitation also was on our calendar without any interaction. That included everything from highly customized message down to a simple text message.
Success Rates:
  Microsoft Outlook (99%)
  Google Gmail/Calendar was second best (90%+)
  Yahoo (95%+)
  AOL (>5%)
  Self Hosted, various applications (<70%)

2. AOL (if you use it for calendaring and not just email) failed almost 100% of the time.  The client just refused to accept our calendar invitation - not matter how we changed and adjusted it. There are still millions of AOL users, although it is not used often as a B2B platform, and it is unknown how many us their calendaring - but from our tests, if you are sending any type of invitation to AOL, you will have a higher failure rate.

3. Mobile clients work seamlessly. I know, most of you just take it on faith that a mobile app/client will work just as well as a desktop app/client. And for those people who use their phones for everything, both business and personal, that's a reasonable expectation. But, it's not 100% accurate.  After our testing, we found functionally, mobile calendars work - what they presented on screen, isn't necessarily the same. Where a desktop notification might be well formatted, the mobile notification for the same event may have HTML leakage.  Not the biggest deal in the world, but it can happen. If you are doing lots of design and have an expectation of that design being presented on a mobile phone - just remember, there is probability is won't.

Our recommendations, especially when using 31Events to send calendar invitations are:

1. understand your end user, what email/calendar system they use, so you can understand the potential for failure rates.
2. Keep your messages on your calendar invites short - we found less than 100 words worked best.
3. Limit "design" for calendar invitations. I'm sure this will change over time, but right now, limited formatting of your message is best.
4. Use one location type. If it's online, just enter the full URL (with http:// or https://); if it's an address, use the full address including the Zip Code.  If you want it work properly use only one - you can put more details in the message area.
5. Who's time is important? For most invitations, this is going to be YOUR time (webinars, webcasts, deadlines, etc) - but there may be times when THEIR time is important - create your invitations accordingly.

Calendars are going to become more and more important as a marketing tool over the next few years, as our marketing campaigns become more and more time sensitive. Right now is a great time to start understanding how the calendar works and how to leverage for your campaigns.