There is no easy solution for this. You add a placeholder which is replaced by a certain answer. If there is no answer the placeholder shows an error.

You can either not use conditions and make all questions mandatory or not use placeholders in your confirmation email.

A long term solution would be to check each placeholder if it's empty and if so place a string like "no answer given" instead of the error message.

@Mazi
Another long term solution could be to have multiple confirmation emails, based on conditions.

"Another long term solution could be to have multiple confirmation emails, based on conditions."
I don't think this is a suitable solution because it's really complex and conditions currently can only be applied to data within a survey.

Can you add the "check each placeholder if it's empty and if so place a string like "no answer given" instead of the error message." solution to our idea tracker at http://ideas.limesurvey.org?!
Thanks!

On which idea?

Just add a new idea describing your problem and add your and my proposals as possible solutions so we can think about how to implement this in a future release.
Thanks!

Idea can be found here: http://ideas.limesurvey.org/ideatorrent/idea/152/