"Windows Mail can compact the message store"

[Will]

From past threads, I understand it is advisable to click "ok" when this
message pops up. My follow-up question is this: What happens to my emails
when the message store is compacted? Will my emails be lost permanently?
Thanks.

 

[Gary VanderMolen \(MVP\)]

It should not affect your emails at all.
Nevertheless, it is always wise to have a backup of your important emails.