I have just switched to Thunderbird from Gmail. Have tried several times to send bulk emails but always get this message: Sending of the message failed. An error occurred while sending mail. The mail server responded: We have detected an unusual amount of suspicious mail originating from this address. Please try again later.. Please check the message and try again. I have a need to send emails frequently to more than one address and this is going to be most inconvenient if it can't be fixed. Is there a setting somewhere? Thank you.