Gmail File Transfer. At the top of the contacts you can see one arrow mark for opening contacts in new tab. Select google csv format.
Then click on required email to open it in desktop. The gmail attachment size limit for incoming emails is 50 mb. Next enter the admin id p12 file path and application id for both.
You can only use a version of outlook that has filein the left corner it means your version has an importexport wizard.
Send download link via email receive a link for the download file in your current gmail address. From the source gmail account the one that has the emails you want to transfer open settings from the options menu and then go to forwarding and popimap. Add to drive place the download file in google drive. On the right side screen you can see different items related to your google account.