- Very good: 

'''Background''' I am currently migrating from Windows to Linux/Ubuntu (finally). So I am a beginner in Linux (intermediate in Windows). As part of this I need to replace my Microsoft Outlook. In Linux there are a few to choose from. For example: Evolution, KDE Kontact/KOrganizer and Thunderbird. Aside from some compatibility issues with G-mail, I was overall happy with Outlook for the following reasons – which are also what I wish I could get out of, preferably one, or more, equivalent personal information manager programs (PIM) in Ubuntu: * '''Calendar''' - Absolutely ok. - Good overview and synchronization with other parts of Outlook - Stylish, useful and clear graphics * '''Task function (To-do)''' - Very good: - Shown in all views (email, calendar) - Good time division: Today, tomorrow, this week, next week, month, etc. * Great possibilities for setting up and designing your tasks (in everything from designing quite complex projects to graphic outline and layout) - Completed tasks are saved automatically and are very easy to access in a separate window (to the left of current and upcoming tasks), where all tasks are also searchable through the search function at the top. Very useful when you need a history of various projects/tasks, etc., that you have completed. For me, absolutely crucial! - Good synchronization with the calendar: Shown, for example, at the bottom of the Calendar for each day. - Quite stylish, useful and clear graphics * '''Contacts/Address Book''' - Also quite ok - Synchronized with other parts. - Stylish, useful and clear graphics * '''Email''' - Quite ok, apart from the aforementioned synchronization problem with G-mail - I completely abandoned IMAP and switched to managing all email online, which is an obvious deterioration: G-mail online is not the world's most intuitive tool for someone who handles large amounts of email with the administration and control needs that this entails. - Plenty of settings - Quite ok synchronization. - Stylish, useful and clear graphics The version of Ubuntu I'm using is 24.04. It comes with Thunderbird. But only as an email client (no calendar, no To-do app, no address book, etc.). Which was a bit of a disappointment. It's a full-fledged PIM that I need. So to start with, I tried Evolution. I don't want to say that Evolution is bad, but it didn't work for my purposes - and in many respects felt quite outdated. Maybe it would be possible to get more out of it if you explored and tested it more, but after a couple of weeks of evaluation, I set my limit. But I really liked that it was synchronized with the calendar that is included by default in Ubuntu (and which is accessed from the bar at the top of the Desktop): Everything you put in Evolution is automatically put in the Ubuntu calendar, and vice versa. Great when you want to quickly access this kind of information. Right now I'm investigating Thunderbird. So I already have the email client (not yet tested, but investigated in terms of settings, etc., etc.). For this I now need the other mentioned parts (especially calendar and To-do) – and get them to work as described above. Since there are such a lot of add-ons/extensions for Thunderbird, I find it quite difficult to navigate and confusing to find out exactly which add-ons/ extensions could correspond to the expectations/requirements I have for those, which I hope to be able to get help with here. Regarding the calendar, the searches I have conducted several times have suggested the extension "Lighting" (https://www-archive.mozilla.org/projects/calendar/lightning/download), but based on the information I have obtained so far, I am unsure/doubtful whether this extension (which, if I understand the matter correctly, is in principle equivalent to the stand-alone application "Sunbird") will meet the criteria I have listed above. Especially when it comes to the Task function. So the question is: Which extensions, corresponding to my wishes/requirements, should I choose in terms of calendar, To-do, and address book? Or are my criteria such that there are no such corresponding add-ons/extensions at all? Or is it better to download some other version of Thunderbird where all of these are pre-installed (and which meets my criteria)? Looking forward to any answers that may provide some clarity. :)