I was able to get things working with http://ww.wp.xz.cn/extend/plugins/wp-mail-smtp/ as suggested in another thread, but its a bit of a hack.
Yes- I’m having the same problem, although it never would have occurred to me to check sending mail to a gmail account instead of our private server. I’ld love some insight if someone learns more.
It had been working until a month ago, don’t remember making any changes but I could be wrong.
FYI – I was having this same issue and after updating to Contact Form 7, v 7.2.3.1, the AJAX messages and validation began working normally again.
Thanks for the update Takayuki, works like a charm!
