What should we do to avoid our email invites from getting treated as spam? I have already tried the tips given at: www.limesurvey-consulting.com/how-to-pre...ing-treated-as-spam/ . Any recent cautions added in 2.05??

The spam problem has little/nothing to do with Limesurvey or the version of Limesurvey. Most of them are general problems when you send mass emails. So I doubt that there is anything 2.05 specific.

Holch is right. Try to make the invitation mail as unconspicious as possible to the spam filter you are trying to get past. The criteria for these filters are set by the admins and thus obviously vary from server to server.
In one instance, the solution was sending out the invitations with my full name (instead of only my first name). Seems the spammers often can't think of a fake last name .

How/why emails are treated as spam mostly depends on the content of the email or the way emails are sent. So this is nothing that can be fixed at Limesurvey level.
From our experience switching from default PHP emailing (often used by spammers) to SMTP emailing already helps a lot.

@Mazi: Why are you responding to a 5 year old thread?

Because I just answered a very similar question at our online chat and was pointed to this thread.
I also think it makes sense to share your experience from time to time. The spam issue shows up at our projects regularly and switching to SMTP turned out to be a simple but efficient solution.

Yes, but don't answer something that are totally unrelated …

It's the final server used : using php MAIL with a valid and good server is better than using a broken SMTP server.

And if you use localhost for SMTP : it's the same things …

Set smtp or php mail don't change anything with the same server finally. And you can set your PHP mail to use a SMTP server by default …