Most common possible causes are 1)The message contains more than 250 attachments. More than 250 attachments cause the MAPI_E_TOO_BIG ...

{4}: Most common possible causes are 1)The message contains more than 250 attachments. More than 250 attachments cause the MAPI_E_TOO_BIG error and 2)Mail has been sent with a malformed addr822 header. Troubleshooting: Reduce the number of attachments in the message, and then resend the message.