Email download problem from hmailserver using IMAP

Hello,
I’m using latest emclient as email client connecting to hmailserver 5.6.6-B2383.

I’m having problems when downloading the email for an offline usage (the customer use the mailbox as a repository to search into old emails) but the download stops.

Hmailserver log reports:

“DEBUG” 6224 “2017-10-11 08:58:56.491” “Creating session 3302”
“TCPIP” 6224 “2017-10-11 08:58:56.507” “TCP - 192.168.88.198 connected to 192.168.88.210:143.”
“DEBUG” 6224 “2017-10-11 08:58:56.516” “TCP connection started for session 3301”
“DEBUG” 6224 “2017-10-11 08:58:59.396” “Creating session 3303”
“TCPIP” 6224 “2017-10-11 08:58:59.404” “TCP - 192.168.88.198 connected to 192.168.88.210:143.”
“DEBUG” 6224 “2017-10-11 08:58:59.413” “TCP connection started for session 3302”
“DEBUG” 3676 “2017-10-11 08:59:07.890” “The read operation failed. Bytes transferred: 0 Remote IP: 192.168.88.198, Session: 3301, Code: 10054, Message: An existing connection was forcibly closed by the remote host”
“DEBUG” 4984 “2017-10-11 08:59:07.890” “The read operation failed. Bytes transferred: 0 Remote IP: 192.168.88.198, Session: 3292, Code: 10054, Message: An existing connection was forcibly closed by the remote host”
“DEBUG” 3676 “2017-10-11 08:59:07.901” “Ending session 3301”
“DEBUG” 4984 “2017-10-11 08:59:07.909” “Ending session 3292”

Emclient reports the following errors (errors change from time to time, they are not always the same):

08:27:48.470|03B|   A17 UID FETCH 49719 (BODY.PEEK[HEADER] BODY.PEEK[1.MIME] BODY.PEEK[1.1.MIME] BODY.PEEK[1.1] BODY.PEEK[1.2.MIME] BODY.PEEK[1.2] BODY.PEEK[2.MIME] BODY.PEEK[2] BODY.PEEK[3.MIME] BODY.PEEK[3] BODY.PEEK[4.MIME] BODY.PEEK[4])
08:27:48.524|052|   * 39505 FETCH (UID 49719 BODY[HEADER] {2172}
08:27:48.526|052|   Content-Type: text/html; charset=“iso-8859-1”
08:27:48.526|052|   Exception:
08:27:48.526|052|     Protocol violation
08:27:48.526|052|     Line Content-Type: text/html; charset=“iso-8859-1”
08:49:15.191|03B|   A46 UID FETCH 52214 (BODY.PEEK[HEADER] BODY.PEEK[1.MIME] BODY.PEEK[1.1.MIME] BODY.PEEK[1.1] BODY.PEEK[1.2.MIME] BODY.PEEK[1.2] BODY.PEEK[2.MIME] BODY.PEEK[2] BODY.PEEK[3.MIME] BODY.PEEK[3] BODY.PEEK[4.MIME] BODY.PEEK[4] BODY.PEEK[5.MIME] BODY.PEEK[5] BODY.PEEK[6.MIME] BODY.PEEK[6])
08:49:15.253|058|   * 42000 FETCH (UID 52214 BODY[HEADER] {2300}
08:49:15.308|058|   A46 OK UID completed
08:49:15.309|03B|   A47 UID FETCH 52215 (BODY.PEEK[HEADER] BODY.PEEK[1.MIME] BODY.PEEK[1.1.MIME] BODY.PEEK[1.1] BODY.PEEK[2.MIME] BODY.PEEK[2])
08:49:15.363|058|   * 42001 FETCH (UID 52215 BODY[HEADER] {792}
08:49:15.366|058|   Content-Type: application/pdf;  name=“Stampa Estratto Conto - senza scadenze.pdf”
08:49:15.366|058|   Exception:
08:49:15.366|058|     Protocol violation
08:49:15.366|058|     Line Content-Type: application/pdf;  name=“Stampa Estratto Conto - senza scadenze.pdf”

So is this a client or server problem?

Thanks