SMTP Relay Blocked by ISP Due to Reply To Address Mismatch

A problem that we occasionally see occuring with SMTP is that it is blocked by the customer's local ISP because the reply address contains a domain name that is not hosted in their network.

If this is the case, then your ISP joins a short list of ISPs who do this (Verizon, MSN, Rogers, to name a few).

The primary indications of this are represented by the error "We do not relay" that you are receiving and the fact that it is happening with all outgoing mail.

Most ISPs relay messages through their SMTP servers by the source IP address. Therefore, as their customer, they allow sending of mail through their servers from the IP addresses in their network. And you would have a valid IP as you are their customer and pay them for internet and mail services to and from your workstation. This does not appear to be the case with your ISP.

The only recourse you have is to complain to your ISP. If they will not fix this problem, then you can subscribe to the Alentus SMTP "Auth" service for only $4.95 per month. For the single monthly fee, anyone in your organization from your domain name, can send out using our SMTP mail service.

If you would like this set up, please request it through the Alentus Support Center, by Submitting a Ticket to Sales & Ordering.

You may specify a username and password that your users will put into their Outlook to authenticate automatically into our outgoing SMTP server. This will have no effect on how they currently receive email.

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