Its not a secret, that DNS BL\RBL lists are the most powerful and effective mechanism of anti-spam defense at this time (2015).

How it works?

IP-address of remote host checked against one or more DNS BL lists (free for all by default). If IP-address is in the list - mail session is rejected.

Sometimes it is necessary to determine whether there are enough channels of ground telephone lines, in case if the operator is connected to Asterisk. To collect such statistics in our company, we decided to record every minute (ideally, of course, more often) the number of active calls\channels in Asterisk to file, then plot if required.

There are two steps in the task:

1. Output needed data to file in manual mode.
2. Put the script into cron.

If you accidentally deleted Postfix log files in Ubuntu (or any other system), you can restore them in the following way:

How to find all mailboxes in Exchange 2010/2013 with mail forwarding enabled?

It's just a string in Powersehll:

It's no secret that when you perform backup with Veeam Backup & Replication, sometimes it "forgets" to delete the its snapshots. This leads to the fact that all virtual machine starts to work entirely on snapshot all the time. This is a costly operation, which significantly reduces the performance of the virtual machine.

In addition, system administrators can create snapshot manually and forget about it. We had a case in our company when a virtual server half-year (!!!!!) worked on the snapshot.

Fortunately, VmWare provides a plugin for Powershell, PowerCLI, which you can use to find all these snapshots.

The longer you work with Veeam Backup & Replication, the lower and lower its interface work. Apparently, this is because Veeam stores in database information about all sessions of the interface. Once they become so numerous that queries to the database begin to slow down.

So we need:

1. Set up Veeam to not to store all this unneeded information.
2. Delete existing data from database.
3. Truncate and shrink database.

After performing these steps, my Veeam client started to work much faster.