There could be many reasons a message was not sent or received, it could be the sending and/or receiving email applications, the sending and/or receiving internet connections, the sending and/or receiving servers, spam filters and blacklists, or someone mistyped an email address.
For problems during sending, most times whoever sent the email will get an error message. If you are having problems sending from a VCN account, please get an exact day and time the message was sent so we can check our servers for error messages. Also, you can look at our help section onManaging the SPAM filter, at the bottom of this page, to see if the email was accidentally blocked as Spam.