cloudron mail server shows a strange message in email subject line

[k2300455]

Hi,

I managed to get the Cloudron mail server working with FreeScout. I am hosting FreeScout and using the mail server on the same machine. I can send and receive emails. However, when I send emails I get a strange long number in curly brackets in the subject area:

Example: {#FS:cmVwbHktMtiewkjerLlt........=#}

When I open the email this disappears though. What is this and how can I remove it?

Just a note: I did purchase and add a few modules such as the numbering of the emails module.

[subven]

What happens if you temporary disable all of your Freescout modules?

[girish]

Can you try sending test mail ? That will eliminate whether this is something in the mail server/mail relay or FreeScout issue. As @subven suggested, you should try disabling all the modules and test things as well. The FS in the subject presumably means FreeScout.