Migrating iMail information between computers?

I have been having many problem with my iMail app along with possible hacking my account. I have finally gotten a stable account in iMail on Big Sur but I would like to migrate it to Sonoma (newest update). Is there a SIMPLE procedure for this?

I am hoping that migrate will clear up a problem I have had on the second machine for some time where activations only garner the "Sign in to Gmail" message but will not accept a valid account or password. The iMail had never been set up on this machine and when I tried recently, before Sonoma, it would take two of my accounts but not the gmail one. The Indications seem to intimate an incompatibility between the app and google but since it is an integrated app there seems to be no way to actually reinstall it. This then is the reason for the above.

tks

WGB

p.s. there is no selection under the subcategory for iMail