Well, this is very little information to work with.
Has it worked before with this SMTP server?
Use the same details to set up an account in a Email-Client like thunderbird or something and see what happens. This way we can make sure that there is nothing wrong with your SMTP server, rather than with Limesurvey.
But then, you are using an ancient version of Limesurvey. If this is really a Limesurvey-Problem, there won't be any fixes for your version. You should seriously think about upgrading to the newest version. Yours is more than 6 years old, which is really, really old for a webapplication. It hasn't received any updates or bug fixes for quite a while. Not a good idea to collect data with such an outdated software.
Help us to help you!
Provide your LS version and where it is installed (own server, uni/employer, SaaS hosting, etc.).
Always provide a LSS file (not LSQ or LSG).
Note: I answer at this forum in my spare time, I'm not a LimeSurvey GmbH employee.