part of bytestring in message in .append() includes 'text-align: center;\r\n}</style><!--[if gte mso 9]><xml>'

append always fails on such messages with 
`abort: command: APPEND => unexpected response: b'}</style><!--[if BAD Command Error. 10'`

Some spam emails includes this in body. I pipe incoming emails to spamassassin and pipe back stdout to be appended to spam mailbox. This type of failures always causes IMAPS connection to be closed.

I can reproduce this every time. IMAP server is Microsoft Exchange I believe