IMAP Proxying to an Exchange Server

[Ralf Hildebrandt]

We're proxying IMAP to an Exchange server. One of my colleagues is
getting this when trying to save a message as "Draft" OR as "Sent
items":

Aug 25 13:45:41 mproxy dovecot: imap(froemmel): Error: imapc(exchange-imap.charite.de:993): Command '7 APPEND "Entw&APw-rfe" (\Draft) {232572}' timed out, disconnecting
Aug 25 13:45:41 mproxy dovecot: imap(froemmel): Debug: imapc(exchange-imap.charite.de:993): Disconnected
Aug 25 13:45:42 mproxy dovecot: imap(froemmel): Error: imapc: COPY failed: Disconnected from server
Aug 25 13:45:42 mproxy dovecot: imap(froemmel): Disconnected: IMAP session state is inconsistent, please relogin. in=232719 out=826
Aug 25 13:46:07 mproxy dovecot: imap(froemmel): Error: imapc(exchange-imap.charite.de:993): Command '7 APPEND "Entw&APw-rfe" (\Draft) {232572}' timed out, disconnecting
Aug 25 13:46:07 mproxy dovecot: imap(froemmel): Debug: imapc(exchange-imap.charite.de:993): Disconnected
Aug 25 13:46:07 mproxy dovecot: imap(froemmel): Error: imapc: COPY failed: Disconnected from server
Aug 25 13:46:07 mproxy dovecot: imap(froemmel): Disconnected: IMAP session state is inconsistent, please relogin. in=232719 out=826

How can I debug this further? I cannot see which commands are sent by
Thunderbird...

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