220 mail.topologyconnect.com esmtp

It looks like you've provided an email header!

Here's a breakdown of what we can infer from the header:

• 220: This is the SMTP response code, which indicates that the mail server is ready to receive mail.
• mail.topologyconnect.com: This is the domain name of the mail server that sent the response.
• esmtp: This is the protocol used by the mail server, which stands for "Extended Simple Mail Transfer Protocol". ESMTP is an extension of the traditional SMTP protocol that allows for additional features and commands.

In summary, this email header indicates that the mail server mail.topologyconnect.com is ready to receive mail using the ESMTP protocol.