One of the most painful aspects of being part of a large business these days is calendaring. Everyone seems to be using a different email tool and there's no universally adopted caledaring tool at Yahoo. Not Yahoo! Calendar. Not Microsoft Outlook/Exchange.

I kid you not. Locating free times is a painful process. Scheduling a conference room is too. Many hours per month are wasted trying to coordinate basic scheduling tasks.

Get Thunderbird But enough people do use Outlook that I find myself having to deal with meeting invitations from them in Thunderbird, my email client of choice. It's a bit buggy and quirky but generally quite flexible and smart. But it has no built-in calendar or ability to decode the vCalendar data embedded in meeting invitations.

Since I have an irrational fear and mistrust of Outlook (see also: email viruses, evil empire), switching is not an option for me. Perhaps that'll change over time.

Last night I discovered the Lightning Project, an extension which aims to provide integrated calendaring in Thunderbird (not to be confused with Mozilla Sunbird or Mozilla Calendar).

Since Sunbird isn't ready for prime time, I installed Lightning and quickly concluded that it sucks ass. I once again found myself in disbelief at the complete lack of good support for something so basic.

But then I noticed something. As a byproduct of installing Lightning, meeting notices now have explicit .ics file attachment. I can double click and open it in Outlook.


After some futzing around, I quickly figured out that I can use Outlook merely as a calendar "helper app" for Thunderbird. I just disable its automatic send/receive email and made sure that it uses the right mail server to send meeting acceptance responses.

Kick Ass!

I now have the best of both worlds (for limited values of "best").

Posted by jzawodn at April 12, 2006 07:57 AM

Reader Comments
# Raymond Yee said:

On a related topic, do you have any word on when the Yahoo Calendar APIs will be released? They were announced at ETCON 2006 ( but I've not seen any sign of them since. With such APIs, I'm hoping to be able to write my own synchronization tools among the many electronic calendaring systems I use!

on April 12, 2006 08:24 AM
# Jeremy Zawodny said:

It's coming soon, but I can't say exactly when--mostly because I don't know. I'll check and see if there's a fixed date.

on April 12, 2006 08:29 AM
# Anjan said:

I was going to say that Outlook/Entourage works well with iCal but then I realized you do use the "evil empire" software :) I have Exchange 2003 at work which I access through Entourage at work. A Paul Berkowitz sync script regularly sychronizes the exchange calendar with my iCal. Using .Mac service, I have my calendar on my MacBook Pro or any other Mac I use.

All I need now is a web interface to the calendar data on .Mac and then I can access it from any connected machine...

on April 12, 2006 09:01 AM
# Marc said:

I'm amazed that no one seems to have solved the email/calendaring problem. I've looked at Sunbird and Chandler and all kinds of other stuff but it pretty much all sucks.

And it's a mess. Some people send me Outlook meeting requests, others send me iCal ones, and the majority of people send me "are you free at 1? 2? 3? 4?" because none of the tools work that well anyway.

I have even less options since I'm on a Mac so I can't even use the Outlook trick that you mentioned.


on April 12, 2006 09:23 AM
# pmp said:

I use mutt.
Therefore, I am screwed in many ways.

I don't want anything fancy (like finding free times, booking rooms, etc), just a way to view the Outlook Calendar attachment and get the relevant pieces. I then manually enter these into my Yahoo! Calendar and that is fine.

I wrote a mutt auto_view extension that does basically what I need and once the Calendar APIs are available, I will extend this again to automatically update the calendar.

on April 12, 2006 09:25 AM
# Andy said:

I use the Mozilla Calendar extension for Thunderbird. While it does (kind of) suck, it some some ways it sucks less than Lignting (recurring reminders actually work, for example). It does have some bugs which they aren't going to fix (because they're working on Lightning now), but for me it works well enough until Lightning becomes usable.

on April 12, 2006 09:41 AM
# Mike said:

The problem is that "the problem" has been solved. Just get everybody to drink the MS koolaid (or Lotus koolaid, or even the Oracle koolaid) and voila! Group calendaring works great. You can see everybody's availability. You can schedule conference rooms. It's easy and reliable. It just requires a homogenized environment. All of these tools are proprietary with limited support of "standards" (do any of the standards encompass everything that Exchange/Outlook does?) So when you have a hetergenous environment such as at Yahoo, you wind up wasting thousands of person-hours on calendaring. Which is why a lot of companies do their own "standardization" and force everybody to use the same thing.

on April 12, 2006 10:51 AM
# COD said:

I use Outlook as a calendar help app - like you do. I also sync Yahoo and Outlook calendars - since my wife and I use a Yahoo calendar to organize our lives.

I look forward to some glorious future where I only need one calendar.

on April 12, 2006 10:54 AM
# Brian M. said:

>Since Sunbird isn't ready for prime time, I installed
>Lightning and quickly concluded that it sucks ass.

I'll admit that they don't do a very good job of labelling it as "pre-alpha" on the Lightning homepage, but 0.1 version number should have been a signal to not get your hopes up.

A wise old programmer once told me that if I ever hear the word "calendaring" in relation to a project that I am assigned to, I should run like hell in the opposite direction. General calendaring is a very hard problem because so much of it is arbitrary and conflicting rules. I'm impressed with anybody that even takes a shot at it, and I'm not surprised if they don't release a good product, especially at version 0.1.

on April 12, 2006 01:27 PM
# marc said:

STOP the madness... Y! calendars UNITE!!!!

on April 12, 2006 02:36 PM
# Sam said:

How many staff members does Mozilla Corp/Foundation have working on calendaring? More than 1? Don't make me start a search-box-revenue-boycott!!! With an excess of revenue right now, I look first to Mozilla to solve this as they have solved my browser and email client issues with such satisfaction.

on April 12, 2006 06:12 PM
# John said: is now live...

Jeremy is right:

Google is Building Yahoo 2.0

on April 12, 2006 10:19 PM
# said:

You're a bit harsh on Lightning really. They only just released version 0.1 recently! It's nowhere near ready for serious use yet.

Compare Firefox now with Phoenix 0.1 :)

on April 13, 2006 02:28 AM
# Bharath R said:

Remember this post Jeremy?

Your wish is now fulfilled!! :-)
Google cal is here & it's simply ubercool!! Go google cal !!

on April 13, 2006 03:33 AM
# Seyed Razavi said:

Interesting timing on this post given Google calendar is now up.

on April 13, 2006 03:59 AM
# xReator said:

Since I have an irrational fear and mistrust of Outlook (see also: email viruses, evil empire), switching is not an option for me. Perhaps that'll change over time.

on April 13, 2006 06:00 AM
# Rob Said said:

vCalander is a great format. It's a pity that some calander apps don't support it. Even recently released ones!

on April 13, 2006 06:09 AM
# huatong said:

Hi, Jeremy: A review on Google Calendar, please.


on April 14, 2006 05:31 PM
# Mike said:

This is something I recently started doing myself, thanks to my desire to keep my calendar/tasks synced up with my Windows Mobile Smartphone. There's absolutely no way I could switch from Thunderbird to Outlook for mail.

I've been waiting for Lightning to be mature for a couple years now, and it's just not possible to keep waiting. Hopefully this will turn out to be a decent setup, so far it's not too bad.

on April 14, 2006 08:11 PM
# Jeremy Johnstone said:

So how does Gcal have anything to do with Jeremy's problem? While it does import pretty decent (not great, but decent), where are the export options? Where is the find free/busy information for your invitees? How do you reserve a conference room or find out if one is even available? While Gcal is a moderately useful "personal" calendaring solution, it's far from being enterprise ready (if they even intended to ever be in that market to begin with). I've heard rumors that internally in Google that many are VERY dissatisfied with the functionality in Gcal and are pushing the company to adopt a third party calendaring solution for internal use. If even Google employees don't want to use it for their work scheduling, somehow I doubt anyone outside the company will.

on April 23, 2006 08:45 AM
# si said:

fwiw, I use lightning (nightly) with thunderbird hooked into my remote google calendar (iCal read-only).

So...I have to create the event in google calendar in firefox instead of having thunderbird/lightning automatically create it for me, and it currently isn't able to send accept/decline, but it's good enough for my needs!

I agree with Jeremy Johnstone (above), Google Calendar it's not "enterprise" ready for work scheduling.

on August 2, 2006 01:27 AM
# Richard Harlos said:

As an employee using a company-provided computer I always used the Microsoft Office products as required but at home, I chose years ago not to use, or even install, MS Office on my personal computer.

Recently I began working from home as an independent contractor and needed calendaring functionality. I already use OpenOffice, Firefox and Thunderbird and when looking at my calendaring options, decided upon the Lightening v0.1 extension for Thunderbird.

My calendar requests coming from co-workers who do use Outlook contain exactly 4 visible items:

1. Invitation from null
(where 'null' is the literal text to a
mailto: link to the sender's email address)
2. Topic: (meeting subject/topic line)
3. Start: 11:00:00 AM
4. End: 12:00:00 PM

Then, of course, followed by 'accept' and 'decline' buttons that will invoke MS Outlook as a helper-app _if installed_.

Ergo, my predicament: I don't have MS Outlook installed, and I certainly don't want to install it just to get this fundamental ability to [a] read a meeting/calendar request and [b] respond to it.

If anyone reading this can suggest a non-Microsoft solution to my wants/needs, I would be enthusiastically grateful!

Thanks in advance!

on August 10, 2006 08:38 AM
# rws said:

Lightning just got MUCH better. Give it another try.

on November 23, 2006 11:29 PM
# AGODAMI said:

Dudes and Dudettes, Lightlning still blows... I can't initiate a meeting or appointment invite.

There are blanks to put in e-mail addresses but it's not sending anything to anybody?

ah the frustration.

on January 3, 2007 11:57 AM
# foxfair said:

have you ever tried this?

You're Invited! is a fix to allow Apple Mail to send Outlook Meeting Invitations to iCal correctly

on February 1, 2007 05:31 PM
# Raj said:

How about Evolution, it is supposed to be able to sync up with Outlook calendars, and is free/open source.

on June 27, 2007 08:36 AM
# LookoutforChris said:


Works fine here. I regularly add "attendees" to meetings/appointings, you just have to check "Send attendees invitations via email". And I regularly receive invites from other users using ical calendars, I just click "accept" and it adds it my calendar. Take another look at lightning/sunbird, it's getting better every release, and it integrates with Gcal now with the Provider extension.

on August 1, 2007 09:27 PM
# Sean said:

Agodami is right. Running Lightning 0.5 with Thunderbird -- "Send attendees invitations" box is grayed out and cannot be selected.

on August 18, 2007 04:59 PM
# Sean said:

And yes, I'm also running the Provider extension for Google calendar.

on August 18, 2007 05:01 PM
# John said:

Thanks for the tips, but I think Lightning will work fine for me. What issues did you see with it?

I use google calendar for my "RL" events - SMS messages for the win. Meetings and calls at work I would like to keep on a work calendar and be able to accept people's invitations - lightning appears to have that functionality so far.

I will post back if I find something that makes it suck for my purposes though.


on September 18, 2007 08:24 AM
# Will said:

I am having the same issue. I cannot get the "send invites" checkbox to check's greyed out. Is this a bug or a setting that I have wrong??

on September 18, 2007 01:19 PM
# Brad said:

Lightning 0.7 doesn't allow for explicit ICS attachments as indicated in this post. I tried to install the 0.1 version, but it's not compatible with Thunderbird 2.0+. Has anyone else come up with a way to do this?

on December 10, 2007 07:35 AM
# Chris said:

Any update on this? It's an incredibly important issue for anybody doing business in 2008 :) Why is the option to send an email grayed out?!

on January 4, 2008 09:53 AM
# Jason said:

All it needs is a simple Thunderbird extension to create a .ics file whenever the email has a MIME content type of 'text/calendar', surely?

The ics file will then be opened by the associated application (Outlook Calendar, iCal, whatever) and then we can all go home for tea and medals.

This is a major bug-bear for anyone in a vaguely commercial outfit and seems simple to fix. Argh!?!

on January 9, 2008 02:57 AM
# Manu said:

I was facing the same problem and I just installed the latest version of Lightning.

Well, you can accept and decline Exchange invites with Thunderbird + Lightning now!

But it doesn't seem to be capable of sending invites.

on March 28, 2008 06:19 AM
# Raul Correia said:

There is bug concerning this filed in bugzilla. The bug is titled "Outlook 200x does not recognize iTIP/iMIP invitation because of MIME type issues".

Here's the link:

on March 28, 2008 08:36 AM
# Howard B. said:

"I installed Lightning and quickly concluded that it sucks ass."

How sad over 2 years after you wrote that statement I still agree with it 100%.

If anyone knows of a solution that will allow a Thunderbird/Lightning user to seemlessly Accept/Decline invitations to meetings (incl. recurrance) from Outlook users please let me know...

Lightning is able to send a *.ics file attachment which Outlook users can now double click and see as a standard calendar message.

on July 21, 2008 07:13 AM
# merganser78 said:

"Lightning is able to send a *.ics file attachment which Outlook users can now double click and see as a standard calendar message."

I think many people's computers aren't set to use Outlook to open .ics attachments by default, so all they get is an email message saying you accept or decline. (At least I had to manually set Outlook as the default program for .ics) If Outlook is not set to open .ics attachments, then they will manually have to mark you as accepted/declined. You'll get a lot of "what the?!?" emails if you work with people like I have in my office...

Wish I could get rid of Outlook altogether... contact sync for blackberry is all that is holding me back now

on July 23, 2008 06:23 PM
# slippi said:

Did anyone manage to get the grayed out "send invitation to all" to work yet? I tried this option with a GCal and added some recipients, clicked on them in the appointment window and chose to send an email to all. A new email to the recipients is opened but no calendar details/ics-file added.

I tried the same with a local calendar and it worked instantly.
So does this feature not work with a google calendar?

I couldn't find it the bug report on it. If anyone has a link, i'd appreciate that!

on September 1, 2008 03:40 PM
# Alle Meije said:

I'm using ThunderBird in Debian Linux (so it's actually called IceWeasel, but it really is ThunderBird. It really is).

My university uses an Exchange mail server that has calendar functionality etc, the whole lot. Very fancy. But it only works if you use Outlook (not possible outside Windows) or webmail in IE (not possible outside windows, nut trusted inside Windows). The webmail interface lacks important features (such as text search!) in FireFox.

Does anyone know an open-source mail program that has access to all the Exchange functionality? Apparently Entourage has access to it (but then that's Mac, which is even more proprietary than MS).


on October 28, 2008 09:26 AM
# Alle Meije said:

... and Lightning (sadly) does not work for IceWeasel (only for ThunderBird) ...

on October 28, 2008 09:30 AM
# Yuri Ushakov said:

Finding your post three years later is great. The Lightning Project is much better now. Thanks.

on February 12, 2009 12:35 AM
# Steeve Cayla said:

Same for me, found your post, scrolled to the bottom, and found out that Lightning Project is better. Now using it, many thanks !

on April 8, 2009 11:04 AM
# Michael Powe said:

Well, 4 years later and Lightning still blows. It does have the Google provider, which allows you to view and sometimes change calendar events in (multiple) Google calendars. But, it won't process updates to existing events (you can drag an .ics file onto the calendar and it will set the event). Once the event is in place, you can't update it. Events scheduled by dragging cannot be moved from one calendar to another. Luck of the draw. I have too many clients sending me updates, it's a real need.

I will probably choke down my distaste and go with Jeremy's suggestion of using Outlook calendar for work. That blows too, but it blows less. (To paraphrase a certain mail-client author.)

I hate to give up Thunderbird, but the other option is to go with Zimbra Desktop.

on January 15, 2010 09:28 AM
# Jesse said:

For Alle Meije's question: Have a look at "DavMail Gateway":

I'm using it for mail/calendar/LDAP access from Thunderbird to exchange. Crashes once in a while, but otherwise works like a charm.

on June 23, 2010 09:17 AM
# estrnod said:

I am using Thunderbird 3.1 and Lightning 1.0b2 on Windows 7.

I received an invitation to me (only) for a meeting from someone using Outlook; there is a .ics file attachment in the email when I view it. There is not a button on the email to add it to my calendar, and there does not seem to be any way to add it directly. I can however save the attachment and then use "Events and Tasks -> Import and select the ics file, which adds it to the calendar.

Is there a way to add the invite to my Lightning calendar directly, without saving it to a file first? (Are there any other plugins I need to install, or configurations I need to make to get this to work?


on July 19, 2010 03:04 PM
# Timoleon said:


thank you to help to solve my old problem interpreting Vcalendars in Thunderbird.



on August 5, 2010 02:46 PM
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