Dovecot has some worthwhile instructions here but you can also do it with openssl:

openssl s_client -connect mail.snork.ca:993
* OK [CAPABILITY IMAP4rev1 SASL-IR LOGIN-REFERRALS ID ENABLE IDLE LITERAL+ AUTH=PLAIN AUTH=LOGIN] Dovecot (Debian) ready.

a login "username" "password"
a OK [CAPABILITY IMAP4rev1 SASL-IR LOGIN-REFERRALS ID ENABLE IDLE SORT SORT=DISPLAY THREAD=REFERENCES THREAD=REFS THREAD=ORDEREDSUBJECT MULTIAPPEND URL-PARTIAL CATENATE UNSELECT CHILDREN NAMESPACE UIDPLUS LIST-EXTENDED I18NLEVEL=1 CONDSTORE QRESYNC ESEARCH ESORT SEARCHRES WITHIN CONTEXT=SEARCH LIST-STATUS BINARY MOVE SNIPPET=FUZZY PREVIEW=FUZZY STATUS=SIZE SAVEDATE LITERAL+ NOTIFY] Logged in

b select inbox
* FLAGS (\Answered \Flagged \Deleted \Seen \Draft $Forwarded)
* OK [PERMANENTFLAGS (\Answered \Flagged \Deleted \Seen \Draft $Forwarded \*)] Flags permitted.
* 16 EXISTS
* 0 RECENT
* OK [UIDVALIDITY 1669347300] UIDs valid
* OK [UIDNEXT 101] Predicted next UID
* OK [HIGHESTMODSEQ 283] Highest
b OK [READ-WRITE] Select completed (0.001 + 0.000 secs).

c list "" *
* LIST (\HasNoChildren) "." Drafts
* LIST (\HasNoChildren \UnMarked) "." Spam
* LIST (\HasChildren \UnMarked) "." MyShit
* LIST (\HasNoChildren) "." Sent
* LIST (\HasNoChildren) "." INBOX
c OK List completed (0.003 + 0.000 + 0.002 secs).

d logout
* BYE Logging out
d OK Logout completed (0.001 + 0.000 secs).
closed