4795209 on "[Plugin: Contact Form 7] Failed to send your message. (orange border error)"

I've been having this same problem but do not use any kind of comment blacklist at all. I set the form to send e-mail to my domain name e-mail account and the plugin has worked well in the past for a long time but recently has become sporadic. Can you please Takayuki?
聖霊は、あなたと兄弟である。