Some email apps have integrated calendars like those in:
Bluemail - https://bluemail.me/calendar/
and
Spark mail https://sparkmailapp.com/features
These are but a few. This would be a great addition to K9.
Does else anyone think it would be worth trying a crowdfunding campaign to raise funds for development of an integrated calendar in K9 5.8? Are their other ways to raise funds for this if K9 thought it worth while?
Hi!
To be honest, I donāt think this is within the scope of K9 Mail. There already are nice and free calendar apps out there and maintaining a basically separate app is a lot of work (which does not stop after initial development).
What advantages do you expect from having the calender app integrated into the email app?
Oh please no!
K-9 is an email app and does exactly what it should. I see absolutely no reason to add bloat like that, itās what Outlook would be for. And besides, every Android device already has a calender on it anyway.
Hello back! Thanks for the response! 
Oh I was not suggesting you make a separate calendar app, I know maintaining an app takes a lot of work. What I suggested a calendar be built intoā¦ K9 mail. Like the two examples I mentioned.
I did send two links in my initial post to show you what I mean. So you could see and get an idea.
Here is Bluemail video for another example - https://www.youtube.com/watch?v=cj2Wmf1GPzU
What I think people can gain by having K9 have a built in calendar would be to mirror the workflow of their email. Most email services provide the big 3; email, contacts, and calendar. It just makes sense to me if web-mail gives people those 3 functions in 1 unified service, and my desktop application also provides integration with all 3, having a mobile app that mirrors the same workflow would be a big benefit. After all most people do not have an email service with email and contacts only, then go to a third party for calendar functions for their desktop. There are a few email services like that but not convenient for most as appointments are in the emails that need to be added to the calendar. On desktop this is done all in one go. I would think keeping the workflow consistent between all platforms would only contribute to K9, not take away.
Again this is just a suggestion. Either way, I think K9 is great and canāt wait for all the great things K9 will provide users when 5.8 roles out. 
Integrating is basically the same amount of work that it would be to write a completely new app. K9 is mainly developed by a single person (not me) and the workload maintaining a second app on top will likely be too much, independently from the money.
I agree that this totally makes sense on a desktop or on the web because it allows to integrate features. Examples could be picking a contact when sending an email or having contactās birthdays appear in the calendar. On desktop, those things are not possible when using separate applications.
Because of the way Android is built, this is not necessary there, though. Any email app can integrate with any contacts app - you can pick whatever app you like and they will still play along. So instead of having a good email app with okay-ish calendar functionality, on Android, you can search for the perfect apps for all of the 3 features individually. They can still integrate as if they were one single app.
It sure didnāt hurt to make the suggestion. I do appreciate the insight though.
I am looking forward to 5.8!
Outlook Calendar integrates with Outlook Mail. I am currently using Gmail. Can anyone recommend a calendar without integrated email?
@alinabo12 There are a few but the one that first comes to mind is Etar Calendar. It gives you both the option to make a local only calendar or sync to whatever calendar you want.(You would want to install DAVx5 for CalDav sync if you ever change your mind). Just go to the settings and select āAdd Offline Calendarā. Itās on both GooglePlay and F-Droid stores, or you can download the apk directly from the F-Droid website. The links are below w/ screenshotsā¦
As a few have already mentioned, it would be a bloat to add an entire calendar app in k9 yes, but to add calendar events support is much needed.
K-9 is an email app and does exactly what it should. I see absolutely no reason to add bloat like that, itās what Outlook would be for. And besides, every Android device already has a calender on it anyway.
You donāt need to add entire calendar app within k9 for that. k9 just needs calendar access. Whenever an email is received with a calendar event/invite, it can be just added to calendar automatically similar to how Gmail/Outlook does. Albeit it adds the events to their own calendars like to Google/Android calendar and outlook calendar respectively. K9 would just add to whatever calendar it has access to as an app.
Besides, nowadays supporting calendar events is considered a commonly used and standard feature for email/email app providers.
What advantages do you expect from having the calender app integrated into the email app?
Say someone creates an event in their Google/Outlook calendar and invites you to join. This invite comes to you as an email in k9. And if k9 would support it, then it would be automatically added to your device calendar regardless of the calendar app you are using. It is very useful and much needed in a daily driver email app, especially for people using de-Googled devices. Remember, the point here is to add only the calendar events support. Not add the entire calendar within the app. It is pretty straight forward to do that AFAIK.
At the risk of necro-ing an old thread, Iām sharing because info on this topic was difficult for me to find. Iām using K-9 Mail for work email (Outlook/Office365) on a Pixel running GrapheneOS, but with no integrated calendar to show work appointments and meetings, I needed a workaround. I also use Fossify Calendar from f-droid.
If the sync accounts in question allow you to publish your calendar as an *.ics link, you can use ICSx5 from f-droid to sync the calendar, then choose to sync the subscribed calendar within Fossify Calendar. Hopefully this helps someone.
Not having an integrated calendar makes k9 mail largely useless. Back to outlook and goodbye to privacy it is
In my opinion, K-9 integrates well with Business Calendar 2.
What? K-9 is an email app, and there are several excellent calendar apps available for Android (I use ETAR and Fossify calendar apps)
Why try and āintegrateā two functions that are completely different? Itās like saying that a Contacts app is completely useless because it doesnāt gave an integrated word processor 
This thread goes back to 2020 where the situation was certainly different. With Thunderbird for Android gearing up and being based on K-9 Mail, considering a calendaring feature seems a little more likely.
There are certainly folks who prefer to separate responsibilities and use a different calendaring application. Iād say the future will either hold better abilities to hand off invitation emails to other calendaring applications, or have an integrated calendar similar to how Thunderbird Desktop has it integratedāor both!
While calendar functionality isnāt on the immediate roadmap, Iād encourage someone to make a post on Mozilla Connect, so we can gauge interest.
Personally Iād hate to see bloat like that added to K-9. I use + love it because itās āonlyā an email client, none of the clutter and extras that Thunderbird for example has.
Why not make it an add-on? That way those of us who donāt need a calendar, tasks, chat or whatever other bloat can simply not install it.
K-9 is nice and slim and JUST an email client ā¦ keep the clutter out of it please 