pop sent mail folders not visible

That's part of my point -- I don't know. It's a POP folder, and "Mailbox behaviors" does not list any information about the "sent folder" at all. The icon on the left of mail does not match what I know I sent, and can see in "recent" mail or a "smart folder" pointing at the "sent" subfolders. I also does not match the "sent" folder on the mail server. It seems to me that having "sent" show subfolders, just as the other do, is all that's needed.

I'm trying to convert usage to IMAP, even though IMAP does not seem to support what I want.

Thank you.

Trying to avert long-winded explanations.... And I am re-evaluating which e-mail server to use. Two servers I'm exploring now is spectrum (that uses cfl.rr.com for me) and fastmail (that uses fastmail.us for me). Spectrum now has only IMAP; it replaced Brighthouse (same cfl.rr.com address) that used both POP and IMAP. Yahoo! still uses POP and IMAP. I'm trying to migrate from POP to IMAP and see all my locally stored email, which seems to be a problem for me with Apple mail.

POP: I store all my email locally and only keep the last month for access using IMAP by tablet / handheld.

IMAP: stores e-mail on the server, and a local copy (I think),

POP: shows a DRAFT, JUNK subfolder called <server> - pop

IMAP: the <server> - pop folder disappears, but the emails are still somewhere locally, but I don't know where.

POP INBOX: shows all my local INBOX email , no matter how old it is

IMAP INBOX: shows only the email stored on the server, but those e-mails are somewhere locally too

Exactly, and that's what I want. POP is designed to do download incoming mail to desktop INBOX and when the "keep on server for one month", then one month's email is accessible on my tablet and handheld. As the mail standard has moved to IMAP, I want to build the same functionality in IMAP -- and I do understand that IMAP is designed to be server based. I also want to do the same with the SENT mail, which I don't yet know how to do either on POP or IMAP.

Bottom line: I want to keep all my mail, current and archive on my desktop, and only the last month on the mail server for access not from my desktop. That functionality has to be done from the mail client, which is Apple mail for me.

Until recently, mail servers gave me the option to use POP or IMAP, but have been recommending use of IMAP over POP. Recently, I've noticed that POP support is being removed from mail servers, leaving only IMAP as the standard. I am trying to custom fit IMAP to the way I use email. In the process, I also noted that I do not understand how Apple mail manages its desktop mail folders. Many years ago, I helped develop Java based e-mail clients, and I understood the two ways the email was stored, but that's not the way it seems to work today.

Side note: Apple manages files (e.g., mail, Photos, music) differently than the way that I do, and the way that I think -- and does not support user modifications. But that is outside this thread.....

Attached is a screen shot of this issue. The "Sent" folder does not have the subfolders as "Junk" and "Trash" (and "Drafts" if it were expanded. "Sent" does not have the subfolders.