I am having an issue with emails not being delivered. It's intermittent but some important emails are not being delivered. Example: on December 5th, an email from an important vendor was sent to all people in my office and not one person received that email. I received an email from that vendor regarding a different matter that day. So, some come through and others are not. We discovered this after the email was re-forwarded to us. We all use Thunderbird for our office email. Any ideas why certain emails aren't delivered while others come through? Many thanks in advance!