Outlook umoznuje vybrat len ssl ako sifrovanie, takze tam nemas co nastavovat...skuil by som ineho klienta, napriklad Thunderbird.
Tazko povedat, kde je problem, pretoze Outlook byva na chyby skupy.
Skusal si to riesit s podporou volny.cz?
Pripadne mozes skusit test cez cmd.
Edit: Cez cmd nemusis, vyzera to, ze to maju ok.

fleg@nhosting:~$ openssl s_client -connect pop3.volny.cz:995 -quiet
depth=2 C = US, ST = New Jersey, L = Jersey City, O = The USERTRUST Network, CN = USERTrust RSA Certification Authority
verify return:1
depth=1 C = GB, ST = Greater Manchester, L = Salford, O = Sectigo Limited, CN = Sectigo RSA Domain Validation Secure Server CA
verify return:1
depth=0 CN = *.volny.cz
verify return:1
+OK BalaPop3 server ready for users @volny.cz