Yeah, it's called Address Book. Can sync with your phone contacts too. Not that you want phones numbers stored in an email client, but it's a good way to have backups too.
I use the Calendar feature very heavily now. So I set up T/bird to view the Calendar. My main use for the calendar is to mark my work shifts, they change all the time, I sometimes get cancelled, etc, etc so it's handy having the calendar as a sort of diary for work, as well as personal stuff.
So I set up a couple of Google calenders for he ability to sync on the mobile too.
I found that using Google Calendar directly was a PITA, and I hate the way it displays, and MS's calendar both on Outlook and the Calendar app in Win10 are pretty useless too.
And for backup I use a program called MozBackup.
Note that over time saving(or archiving mail) does build up some half decent bits and bytes!
I originally came from Eudora(mail client) and I or it lost some mails from work with my pay invoices.
So, tried Tbird, looked good enough, transferred mails easily(which is will also do from any Outlook based system too) I think either before or about '07, so been using Tbird for 10+ years now.
Obviously a lot of email nowadays is primarily junk, but some are keepers(eg. I still have my pre '07 Oziexplorer registration email confirmation).
All those saved/archived mails take up space, even tho the email itself is only a kB or two, the attachments will bloat it. So my current Tbird profile sits at about 3.5Gb, 3.1G of which makes up the archived mails.
All the important profile data is saved in your User/roaming/tbird folder, in there will be a folder with a weird cryptic naming convention eg. Zyx46tJlifX .. or something weird.
All the T'bird data is in here. You could archive just that cryptic folder itself, but as said over time it's size will be quite large.
MozBackup does enough to compress that saved data down to approx half that size(or less).
So as you move your PC needs from one device to another and you stick with Tbird; you install Tbird(DON'T OPEN it tho) just have it installed and before you use it restore the backup via Mozbackup.
I you do a manual folder dragging backup and restore it the same way, you need to open Tbird, allow it to create a profile, then add the profile folder you saved back into the newly created appdata directory.
Once done, you then change profile within Tbird and you're good to go again.

