Cassavant requires that all SMTP, inbound and outbound, conform to industry best practices. Due to requirements placed on the industry, we do not make exceptions to these; however we will work with companies experiencing SMTP issues to resolve the issues so that security and reliability are maintained.
- SMTP TO Cassavant must be secured with TLS. Effective December 1st 2020 we no longer accept messages in plain text.
- SMTP FROM Cassavant will only be permitted to remote servers over TLS and to servers with a Valid TLS certificate from a Trusted Certificate Authority.
- TLS connections are only permitted over TLS version 1.2 or newer.
- Sending e-mail server must provide a DNS Host Name in HELO or EHLO that is able to be looked up via public DNS servers.
- Connecting IP address must have a valid and published PTR/Reverse DNS record that matches the name presented by the sending server.
- Senders domain must have valid A, AAAA, or MX record in public DNS.
- Senders domain name must have a published SPF record.
- Sending and Receiving IP address should not have a bad reputation.
- Sending domain(s) should not exist on any Real Time Block Lists.
- Sending large attachments will likely result in the message being blocked. Please work with your contact at the company to obtain access to our Web Portal for secured file transfers.