TYPO3 Core

Hmm, sounds strange. I'd be very surprised if contact forms on every TYPO3 website could not be used by Opera users...

Can anybody confirm this issue?

I just tried it using Opera 8.5, Typo3 4.0 and a standard mail form. There were no problems.

Thought so.
@Staffan Ericsson: Please provide more details that help to reproduce this. Additionally, please try removing some extensions (temporarily) to see if this solves the problem. My guess is that some extension is causing trouble...

i had some caching related problems with opera too

i used that code to solve it:

[browser = opera]
config.sendCacheHeaders= 0
config.sendNoCacheHeaders = 1
config.additionalHeaders = Cache-Control: no-cache
[global]

i do not know why it worked, but the issue was, that opera didn't send any request to the server. It took the local-cached sites without checking the server. (i used webscarab to track the http-traffic)

Resolved, no change required after no feedback from Staffan for a very long time.

If this really was an Opera issue, it's likely to be solved meanwhile, anyway. Thanks Martin for the caching hack as a workaround.