sieve-manage hangs while connecting

[Herbert J. Skuhra]

Hi,

I am running Emacs on FreeBSD 11-STABLE (i386/amd64) and I have a
strange problem with sieve-manage: the connection almost every time
hangs during sieve-manage-authenticate.

- Run 'emacs -q'
- M-x sieve-manage
- Enter imap server (e.g: imap.mailbox.org)
- credentials are stored in ~/.authinfo.gpg (entering them manually
makes no difference)
- Emacs hangs
- With ("setq debug-on-quit t) and pressing C-q I get:

Debugger entered--Lisp error: (quit)
  accept-process-output(#<process SIEVE> 1)
  sieve-sasl-auth(#<buffer  *sieve nil:sieve*> "PLAIN")
  sieve-manage-plain-auth(#<buffer  *sieve nil:sieve*>)
  sieve-manage-authenticate()
  sieve-open-server("imap.mailbox.org" nil)
  sieve-manage("imap.mailbox.org")
  funcall-interactively(sieve-manage "imap.mailbox.org")
  call-interactively(sieve-manage record nil)
  command-execute(sieve-manage record)
  execute-extended-command(nil "sieve-manage" "sieve-ma")
  funcall-interactively(execute-extended-command nil "sieve-manage" "sieve-ma")
  call-interactively(execute-extended-command nil nil)
  command-execute(execute-extended-command)

- In sieve-manage-log the last lines are:

OK "TLS negotiation successful."
AUTHENTICATE "PLAIN" "..."

- After pressing Q in sieve buffer the following lines are added to
  sieve-manage-log:

LOGOUT
"IMPLEMENTATION" "Dovecot Pigeonhole"
"SIEVE" "fileinto reject envelope encoded-character vacation subaddress 
comparator-i;ascii-numeric relational regex imap4flags copy include variables 
body enotify environment mailbox date index ihave duplicate vacation-seconds 
imapflags notify vnd.dovecot.pgp-encrypt"
"NOTIFY" "mailto"
"SASL" "PLAIN LOGIN"
"VERSION" "1.0"
OK "Capability completed."
OK "Logged in."
OK "Logout completed."
Process SIEVE connection broken by remote peer

Any ideas how to debug/fix this?

Thanks.

--
Herbert