Global signature missing for mutlipart messages

[maxxer]

Hi.

Some of our users have configured their Zimbra 8.8.15 account as external on Gmail (IMAP).
We found out that global mail signature isn't visible for mails sent via Gmail through Zimbra.

Apparently Gmail sends email as multipart, with both text and text/html versions of the message body.

Zimbra embeds the signature only in the text part, unfortunately most email clients will show the html version by default so the signature is gone.

Any workaround or fix to this behaviour?

Thanks