When working on mail flow issues, one of the first troubleshooting steps with any mail server is to try and telnet into port 25 of the server. Exchange has an error, 530, that says that the smtp connection wasn’t authenticated. If you’re trying to relay through an Exchange server, that’s a good thing, as you wouldn’t want an open relay. However, if you’re trying to relay to an Exchange server, that’s not such a good thing. So let’s look at what this symptom looks like. First we try and telnet into port 25 of the server: telnet exchange.krypted.com 25 Which shows the following: 220 exchange.krypted.com Then we say hi: Helo…
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Change MTU in Windows Server
When we transfer certain amounts of data in a packet we might cause that packet to fragment. The less fragmentations without requiring a collision or a re-send of a packet, the more efficient network traffic can be. The MTU defines the packet size. Different types of data or network links respond differently. To change the MTU on a Windows Server we’re going to use the netsh command. First, we’re going to use ping to ping a host on our network, using -f and then -l which allows us to define the MTU size. In this case we’re going to use 1500: ping https://krypted.com/ -f -l 1500 We should get an…