You can find the delivery status of every message sent on MYtxtBOX in the reports section. Here is a list of the delivery status and what each one means.
Delivered: Message has been delivered and recipient’s mobile handset has acknowledged receipt of message.
Sent: Message has been sent to the recipient’s mobile network for delivery.
Pending: Message has been scheduled for delivery.
Buffered: Message has been stored by Mobile Network.
Accepted: Message has been accepted by Mobile Network on behalf of the subscriber.
Undelivered: Recipient is unable to accept messages. This means the phone number may not exist or the recipient’s phone may be switched off.
Rejected: Rejected by network.
Error: Rejected by SMSGH or Message Error.
Blacklisted: A message status is shown as blacklisted when the message recipients notify their network service provider like Vodafone or MTN of their unwillingness to receive bulk SMS messages. This can be reversed if the recipients want to receive bulk SMS messages.