Using SM Free Edition v16.3.6989 on Windows server 2008 R2 (WHS 2011).
Since 3 days the (automatic) POP retrieval is not working anymore for 4 user accounts.
Nothing else has changed.
The (detailed) POP Retrieval Log shows
 [2025.03.16] 21:54:57 [user@domain] [pop.isp.be:userid@isp.be] Connection to xxx.xx.x.xx succeeded
 [2025.03.16] 21:54:57 [user@domain] [pop.isp.be:userid@isp.be] Could not understand servers response to connection
 [2025.03.16] 21:54:57 Finished processing for user@domain
Testing the connection in Settings - Connectivity - Email Retrieval always says "Connection test failed"
No change after restarting SM service or the complete server.
I deleted the retrieval for one user and created it again but don't succeed to save it because the failing test.
Testing via openssl is working fine, connection is ok and retrieving email is possible !
 openssl s_client -crlf -connect pop.isp.be:995 -brief
 CONNECTION ESTABLISHED
 Protocol version: TLSv1.3
 Ciphersuite: TLS_AES_256_GCM_SHA384
 Peer certificate: C = BE, ST = Brussels Hoofdstedelijk Gewest, L = Schaarbeek, O = Proximus NV, CN = pop.isp.be
 Hash used: SHA256
 Signature type: RSA-PSS
 Verification: OK
 Server Temp Key: ECDH, prime256v1, 256 bits
 +OK InterMail POP3 server ready.
 user userid@isp.be
 +OK please send PASS command
 pass **********
 +OK userid@isp.be is welcome here
 stat
 +OK 16 2565548
 ...
I've been looking around (almost) everywhere, but did not find any clue to resolve this.
Anybody to point me in the right direction ?