I am a BT Yahoo user on web mail - through Chrome using Windows 10.
I want to archive a large and old library of emails. I understand that the archive (which cannot use a folder structure) will write the files to my hard drive. I have done a test but cannot find where the archive is located. My concern is that if/when my hard drive corrupts - I will lose all my archived emails. I want to back up the data to an external drive - but need to know where the archive is located.
Any help and guidance would be appreciated.
I have no idea about archiving webmail, but if you set up a mail client to download all the mails (configure it to leave a copy on the server if using POP3) you can use folders and will know where the files are stored on your hard drive so they can be backed up. There are many free email clients to choose from. Claws, EMClient, Thunderbird etc.
MS Outlook is a far superior method of dealing with mail, much simpler than webmail, more secure, no adverts etc etc. Not sure why you think it adds a layer of complexity.
Of all the free email clients I find Thunderbird the least intuitive to use.
If you have a licensed copy of MS Outlook on your machine, I would thoroughly recommend you use that in preference to any of the free clients.