Question Mark ? at the beginning of all emails going out using SMTP

Question Mark ? at the beginning of all emails going out using SMTP

Hi,

Whenever we send an email through automatic route using SMTP from our server, we see a ? character at the beginning of main content of the email.

Sometime back it was not there. But from last 1 month or so it has started. Few of our recipients reported this to us. Attached is the image

Since then we have checked our email templates and not found anything problematic.

Can someone help ?

regards
Nidhi