Hi Frederico,
Thank you for reaching out. I wasn't able to replicate this behavior in my testing.
Are you able to replicate this behavior on demand, or does it happen at random?
Can you please provide the Build number that your server is running? This can be found in the About SmarterMail menu, or in the Diagnostics page.
Thank you,
Andrea Free
SmarterTools Inc.
877-357-6278
www.smartertools.com