All my emails older than 2 years are missing. Does the Mail app automatically delete them or is the setting for that?
Thanks so much for providing that information for us, tmor51,
Since your iCloud email messages utilize the iCloud storage space you have available, we would first suggest seeing if you are low on storage: Manage your iCloud storage - Apple Support.
We would also encourage you to review mailbox size and sending limits, which can be found in the Apple Support article Mailbox size and message sending limits in iCloud - Apple Support.
Best!