Set Postmaster Address

By default, the value of the external postmaster address setting is blank.

This default value sets the external postmaster address to the value

postmaster@<Default accepted domain> for your organization.

There's no mailbox associated with the postmaster@<Default accepted domain> email address.

Set

Set-TransportConfig  –ExternalPostmasterAddress [email protected]

Checking

Get-TransportConfig | Format-List ExternalPostmasterAddress

SendConnector

scoped send connector

When you mark a send connector as scoped, this means it can only be used by Exchange 2007/2010 hub transport or Exchange 2013 mailbox servers in the same Active Directory site as the send connector.

If not selected, the connector can be used by all transport servers in the Exchange environment

send connector Cost

A lower cost value indicates a preferred connector.

If both connectors have the same cost and proximity
 then it will select the connector that comes first alphabetically.

IgnoreSTARTTLS

Set-SendConnector "NoTLS" -IgnoreSTARTTLS $true

whether to ignore the StartTLS option offered by a remote sending server.

Get-SendConnector -Identity "NoTLS" | fl

TLS 的 Log

TIME,Default Sender Connector,ID,2,LOCAL_IP:32630,REMOTE_IP:25,<,220 mail.recipient.domain ESMTP Postfix,
TIME,Default Sender Connector,ID,3,LOCAL_IP:32630,REMOTE_IP:25,>,EHLO mail.sender.domain,
...
TIME,Default Sender Connector,ID,4,LOCAL_IP:32630,REMOTE_IP:25,<,250-mail.recipient.domain,
TIME,Default Sender Connector,ID,8,LOCAL_IP:32630,REMOTE_IP:25,<,250-STARTTLS,
...
TIME,Default Sender Connector,ID,13,LOCAL_IP:32630,REMOTE_IP:25,>,STARTTLS,
TIME,Default Sender Connector,ID,14,LOCAL_IP:32630,REMOTE_IP:25,<,220 2.0.0 Ready to start TLS,
...
TIME,Default Sender Connector,ID,15,LOCAL_IP:32630,REMOTE_IP:25,*,,Sending certificate
TIME,Default Sender Connector,ID,16,LOCAL_IP:32630,REMOTE_IP:25,*,CN=*.sender.domain,Certificate subject
TIME,Default Sender Connector,ID,17,LOCAL_IP:32630,REMOTE_IP:25,*,"CN=Sectigo RSA Domain Validation Secure Server CA, O=Sectigo Limited, ...
TIME,Default Sender Connector,ID,18,LOCAL_IP:32630,REMOTE_IP:25,*,3F349BC877A92D7E3019616D5D4D1F9E,Certificate serial number
TIME,Default Sender Connector,ID,19,LOCAL_IP:32630,REMOTE_IP:25,*,9B9C3D3CB95E0B28D5B0A24E01C207CE4CDFC955,Certificate thumbprint
TIME,Default Sender Connector,ID,20,LOCAL_IP:32630,REMOTE_IP:25,*,*.sender.domain;sender.domain,Certificate alternate names

TIME,Default Sender Connector,ID,21,LOCAL_IP:32630,REMOTE_IP:25,*,,Received certificate
TIME,Default Sender Connector,ID,22,LOCAL_IP:32630,REMOTE_IP:25,*,F982D6962E42F9086416F1920BD18005AA42BE3C,Certificate thumbprint

TIME,Default Sender Connector,ID,23,LOCAL_IP:32630,REMOTE_IP:25,>,EHLO mail.sender.domain,
TIME,Default Sender Connector,ID,24,LOCAL_IP:32630,REMOTE_IP:25,<,250-mail.recipient.domain,
TIME,Default Sender Connector,ID,24,LOCAL_IP:32630,REMOTE_IP:25,<,250-...,      # No "250-STARTTLS"

 * Local 並非用 25/tcp outgoing

 * 用 EHLO 去查 Server 是否支援 STARTTLS

 * 交換 Cert. "Sending certificate" 及 "Received certificate"

 * 第2次的 EHLO 就沒有 STARTTLS