Sporadic `Net::IMAP::ResponseParseError: unexpected QUOTED (expected "]")` on Outlook365

[hoffi]

Sometimes i get random ResponseParseError's when working with Outlook365 mailboxes.
I activated debug logging and found the following log message when the error occurred:

S: RUBY0001 OK [Error="Microsoft.Exchange.Data.Storage.WrongServerException:Cross Server access is not allowed for mailbox xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" AuthResultFromPopImapEnd=0 Proxy=XXXXXXXXXXXXX.EURXXXX.PROD.OUTLOOK.COM:1993:SSL MailboxBE=XXXXXXXXXXXXX.EURXXXX.PROD.OUTLOOK.COM Service=Imap4] AUTHENTICATE completed.
Net::IMAP::ResponseParser parse_error: unexpected QUOTED (expected "]")
  tokenized : "RUBY0001 OK [Error=\"Microsoft.Exchange.Data.Storage.WrongServerException:Cross Server access is not allowed for mailbox xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx\"" 
  remaining : " AuthResultFromPopImapEnd=0 Proxy=XXXXXXXXXXXXX.EURXXXX.PROD.OUTLOOK.COM:1993:SSL MailboxBE=XXXXXXXXXXXXX.EURXXXX.PROD.OUTLOOK.COM Service=Imap4] AUTHENTICATE completed.\r\n" 
  @lex_state: EXPR_BEG
  @pos      : 157
  @token    : QUOTED: "Microsoft.Exchange.Data.Storage.WrongServerException:Cross Server access is not allowed for mailbox xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" 
  caller[ 0]: rbra                           (parser_utils:54)
  caller[ 1]: resp_text                      (response_parser:1887)
  caller[ 2]: resp_cond_state                (response_parser:815)
  caller[ 3]: response_tagged                (response_parser:804)
  caller[ 4]: response                       (response_parser:683)
  caller[ 5]: parse                          (response_parser:40)
  caller[ 6]: get_response                   (imap:3494)
  caller[ 7]: receive_responses              (imap:3396)
  caller[ 8]: start_receiver_thread          (imap:3373)

Currently i use net-imap 0.5.12. But i have tested with the latest version 0.6.2 and parsing also fails here:

Net::IMAP::ResponseParser.new.parse 'RUBY0001 OK [Error="Microsoft.Exchange.Data.Storage.WrongServerException:Cross Server access is not allowed for mailbox xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx" AuthResultFromPopImapEnd=0 Proxy=XXXXXXXXXXXXX.EURXXXX.PROD.OUTLOOK.COM:1993:SSL MailboxBE=XXXXXXXXXXXXX.EURXXXX.PROD.OUTLOOK.COM Service=Imap4] AUTHENTICATE completed.'
'Net::IMAP::ResponseParser::ParserUtils#parse_error': unexpected QUOTED (expected "]") (Net::IMAP::ResponseParseError)

The error looks like something failed internally on exchange.
However the parsing should not fail here, as the IMAP spec seems to allow this as far as i understand it?