20070423
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Parent class notes: Email systems class notes
George's complementary notes
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Email systems
Joe shows us the exchange system they have installed at the district. We see a window divided in two sections: the narrow section of the left has two subdivitions:
- The tree of the folders (inbox, deleted items, sent items, etc...)
- A quick list of features that can be used. Each time you click on any of those features, the other section of the screen comes out with the feature. For example: if you click the calendar, you will see the electronic agenda on the right part of the screen.
When you think about email, you will be thinkig of a number of things.
Joe shows us a sendmail tutorial. George will put a link to it in his notes.
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Mail <User|Transfer|Delivery> agent.
MUA, MTA and MDA are used by the email systems to function.
When you try to send an email to some address, you send a message to a server that contains a mail transfer agent (a smtp). Almost all the time, the server that contains a mail transfer agent is not the server asociated with the ip adrres that is asociated with the address of the site.
So, the firs thing you have to do to is to open a command line to figure out wether or not the server has a mail transfer agent.
So, we open the command line, then we type the command "nslookup", and we set the type of server we are looking for, by typing set type = mx wich means that we are looking for mail exchange agents.
Then we type www.the-page-we-are-trying-to-find-out-the-smtp-.com..., and the program will show you the transfer agents asociated to that domain, and there is a field called "preference" that tells us wich exchanger is going to be used with higer priority (the less this number, the higher priority)
When a mail transfer agent can't send an email for whatever reason, it will stuck the other mail waiting on the queue until it gives up.
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Products to manage emails
There is a pretty good product called qmail. Also we can use Mandrake and other products.
There is another product called send mail. Another called exchange. All of those are email manager agents. This week we will work with send mail and the next week we will work with exchange.
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Experimenting with mail user agents conected o our linux server
We will conect to our linux server using the tunnel as we did in the past (a billion years ago)
If the email doesn't work, sometimes it can be because there is a firewall set. Remember that the port 25 has to be enabled, and the MTA must accept email from TCP/IP
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Sendmail.mc
This generates an object code called sendmail.cf, and it uses a macro generator that is included in linux systems. We don't need it in our system. We only use webmin and it will be done.
