Interop:

https://gsuiteupdates.googleblog.com/2017/07/improvements-to-google-calendar-interop.html

https://support.google.com/a/answer/7444958?hl=en&ref_topic=7437779


Contacts Sync:

http://cloud.sync2.com/pro

https://www.howtogeek.com/202090/how-to-automatically-sync-contacts-between-outlook-and-gmail/

https://sourceforge.net/projects/googlesyncmod/

https://sourceforge.net/projects/outlookcaldavsynchronizer/?source=typ_redirect



IMAP 50GB limit issue with GMAIL and Outlook:

https://answers.microsoft.com/en-us/msoffice/forum/msoffice_outlook-mso_other-mso_o365b/the-message-store-has-reached-its-maximum-size/3ae2ce21-fa36-4a25-9642-880cf43ac383



Caldevsync:

https://caldavsynchronizer.org/download-2/