Basically what has happened in our company is this....We had one isp and one host for our email about a month ago. Since that time we have changed the isp but the email host has remained the same. Since changing out isp we have received bounceback notices from a large number of companies...including Dell, Verizon Wireless, Bain Capital, Bloomburg, etc. If we change our outgoing server settings in outlook from the email host to our isp we have no problem sending emails. But if we use our email host's outgoing server it will kick back after 5 secs of being sent out. Why would changing an isp cause a problem with our email's that are being hosted though a different company? And why didn't we have the problem with out other isp? Thanks for any and all help!