Thanks for the response, Jens. I'm not sure what caused the problem,
as I hadn't made any changes to the server, but I looked into Dovecot
issues (the IMAP software on my server) and I found one related to the
FTS (full text search indexing) that solved the problem:
doveadm fts rescan -u us
David Topping wrote:
Up until several days ago, the results of a search spanned my entire
Inbox (or my entire email account when adding "All Mailboxes" in the
Advanced search options). Recently, my search results only show the last
day or two of results, even though there should be MANY older r
