No, Outlook Users, Calendar Invite Attachments is NOT a Standard E-mail Feature
It all started around 1991 bursting onto the scene as Microsoft Mail for PC Networks v2.1 along with Microsoft Schedule+, basically the long parents of what eventually became what is Outlook today. Though far simpler, the core concepts of the two, a message system, and a calendar, have remained the same for the near 30 years that the systems now support.
Since then Outlook has been ingrained into the Microsoft Office ecosystem, almost became the defacto standard in e-mail the world-over, and has had numerous improvements and functions added, like Signatures, mail merge, contacts, templates, even a plugin API, and integration with other Microsoft communication tools such as Lync (now Skype/Skype for Business).
Each system still has all of it’s core function though, and Microsoft introduced a feature to it’s Outlook environments, around the same time they moved their “post office” software to what is now known as “Exchange”. Calendar Invite Attachments.
Now this all happened around the mid to late 90s, and while Microsoft is still a software juggernaut today, the “openness” of the world-wide-web has slowly but surely seen a decline in Exchange servers, and ultimately it’s no longer a defacto standard even in industry, with Exchange servers only making up 2.83% of total internet connected email servers (Source). The Outlook software is #3 among the top 10 most used e-mail clients worldwide now with only 9% market share compared to the Apple iPhone Mail client’s 27% and GMail’s whopping 29%! Even Outlook.com (their cloud service) is slowly gaining market share. (Source)
So this is where we come to the Calendar Invite Attachment. A super useful tool for some users, but it’s actually not a standard e-mail feature on anything except for Outlook users who utilize Exchange Server.
Seriously. See, the Exchange server, and Outlook client can communicate the file transfer and interpret what they want to send and receive from each other, but if almost any other e-mail server sees an attachment as part of a calendar invite, it pretty much flips out and actually ends up with one of the following things happening.
- Your sendmail server doesn’t know what to do so it just doesn’t send it.
- The receiving server doesn’t know what to do so it doesn’t receive it.
Outlook (and Exchange) treats their calendar invite files as a sort of compressed file (“Zip” format is a compressed file), thus they can “contain” other files within them. However, this is a non-standard function for pretty much every other e-mail server on the planet, and because Outlook, and Exchange, have such a low total worldwide market share, the other developers (even the big dogs like Apple and Google) see no reason to support this in the same way. It’s not a cost effective decision for them to do so.
So now we’re going into the “But wait my Google, Yahoo, etc. Calendar lets me add attachments to those invites.”
Yes, they do, however these actual “attachments” really aren’t, if you click on those attachments in your Google Calendar are actually Google Drive uploads, and Yahoo’s Calendar system works similarly, seriously, click on the links they create, you’ll see that it just takes you to a website to download the file. This means they’re just links.
So, again, sorry Outlook Users, attaching items to calendar invites is actually not a standard function of e-mail clients. If you want consistent attachments on calendar invites across e-mail systems, without your e-mail getting blocked, or failing to send, your best option is to upload to a file sharing site and sharing the link in your invite description.
Now, I do want to go into why I wrote this. It’s actually because for my employment, part of my job is administering a G Suite domain, and while we do enable the Outlook Sync tool for our users who are stuck in the “Using Outlook forever and can’t get use to GMail” side of things, I felt it necessary that I publicize the fact that Calendar Invite Attachments are not actually a default thing for e-mail (even if it “worked in outlook for 20 years”.)
This needs to be public knowledge, as I’ve actually had complaints from my own users, and even our clients because they expect it to work all the time, when it’s actually impossible for it to work all the time, because there’s only one set of e-mail software that actually supports this functionality, Outlook alongside Exchange Server, and nothing else. At least now it’s only these two, Microsoft use to have an Open Source Exchange Server that they shut down years ago, which is why Google had to design their own Sync tool for Outlook users, the Open Source Exchange Server supported the calendar invite attachment.