Does RCN have email restrictions?
Sending Mail: RCN Limits you to 400 email messages an hour per IP address (3000 for static IP addresses) through their mail server cluster. This is done to prevent machines that are hijacked by spyware from sending more spam and infecting more users. *Note: We allow a maximum of 1000 recipients per message as well.. so if you have a static IP address, you can send either 3 message with 1000 recipients on each, or 4000 messages Attachment restrictions: 10mb max mail message size, 6.6mb before encoding.