[MlMt] NUL character warnings (v5246)

[Scott A. McIntyre]

Hi,

For the last few days I've been getting a LOT of these:

Server response: “I71 NO Message contains NUL characters”. Command 
attempted: “I71 APPEND "INBOX.Sent Items" (\Seen) "20-May-2016 
08:01:30 +1000" {696+}”.

The IMAP server is FastMail, but the problem only started happening 
after a recent update in the last week.

I had this issue in the past, and I know roughly how to fix it, but, not 
really sure what's repeatedly causing it.

Anyone else seeing this?

Scott