Stop email accounts updating in Mail App on IPad

I access a number of email accounts, including Gmail, through the Mail App on my iPhone and IPad. It appears that some of my emails (I think mostly Gmails) were moved from the inbox to the bin - maybe human error, maybe some other way (I have secured my gmail acvount). However I frequently empty my bin folder in Mail and did this on my iPhone before realising what had happened.

I am hoping that I can retrieve these ‘permanently’ deleted emails before opening Mail on my IPad. For the moment I have turned off the internet connection on IPad as well as the Mail setting on each individual email account. However although I have not deleted the accounts, I now cannot see any emails at all. Is there a way I can freeze Mail to stop any deletions whilst still being able to view the content? Any help really appreciated.