SMTP Erro

Hi all,

I am currently analyzing a strange error that appeared in the NAV 2009 solution:

When sending purchase orders to approval in RTC the application are returning the following error:
http://s27.postimg.org/ecsalvvv7/asd.png

After a few tests i did noticed that it just happens in RTC and with HTML formatted emails. For example, if in SMTP.CreateMessage i change the HTML parameter to false, it works.

The team have not changed the NAV code recently. It just stopped working from one day to another.

Do you have any hint? Can you help me solving this?

Thank you very much,

João