Zentyal Internal Plumbing (Part I): Mail

Communication, Development  Tagged , , , , , , 4 Comments »

Hello all,

Some of our advanced users don’t have enough just interacting with the Zentyal interface, and want to go deeper in its entrails, to know the abstracted-out details. In this series of small blog posts I would try to clarify how the different components are interconnected.


I want to cover the following sub-systems:

  • Mail (Mail module only version)
  • Mail (Groupware version)
  • Samba4 and Kerberos & how it connects to other sub-systems
  • HTTP proxy

Let’s start with the Mail (Mail module only) and it’s general interconnection map:

(click to enlarge image)

This diagram also includes all the mailfilter capabilities.

Point by point:

A: Postfix is our Mail Transfer Agent, in charge of delivering and accepting mails from other mail servers.

B: The standard entry point for the SMTP protocol, it can support security via STARTTLS. Intended for communication with external MTAs.

C: Same than B, this port is intended for local users delivery.

D: Same than B, but with forced TLS communication.

E: Every time the MTA receives a new message, the associated domain can be checked against the Postgrey database, this mechanism can force retries to deter spamming bots.

F: Dovecot, our Mail Delivery Agent, distributes the mail to the users’ mail boxes.

G: Dovecot is able to accept SIEVE rules (filters, forwards, flags and so on) using this port.

H: SIEVE is sub-systems implementing a scripted language that performs the configured rules over the incoming mail. Take into account that SIEVE rules can, in turn, talk to the MTA to forward a mail again.

I: Your Mail User Agent (mail client) will retrieve the mails from the MDA, using POP, IMAP or their secure versions.

J: Amavis is a security suite that will use other components to filter potentially dangerous mail.

K: Messages are forwarded from the MTA to Amavis, checked, tagged according to their spam status and then returned to Postfix.

L: Amavis uses an unix socket to pass the messages to the ClamAV antivirus for inspection. Infected messages will be stored away in the quarantine folders, thus, they won’t be delivered to their recipients.

M: The Spamassassin suite uses multiple auto-adjusting mechanism to detect unwanted mail.

N: Fetchmail can periodically retrieve mail form external accounts and insert it in our system talking with the MTA.

O: The Webmail service can be deployed to communicate with the MTA and MUA using a webapp.

Hope this had shed some light, the next post will reuse a lot of this concepts.

A post by Mateo Burillo

Remember, remember the month of Movember

Communication  Tagged , , No Comments »

Movember has arrived to Zentyal

Most of you would already know about that annual event called Movember. For those who don’t here is a brief summary: some dudes (Mo Bros) let grow their moustaches during the month of November. So there it is the combination of those two words, moustache and November, that builds the Movember event. I am sure you have noticed some other Mo Bros at the TV or maybe you just thought how horrible was that young guy with that ridiculous moustache. But everything has an explanation.

We let grow our moustaches during the month of November to raise the awareness of prostate cancer, other male diseases and associated charities. We want to “change the face of men’s health”, so one our duties consists in answering everyone who ask us about our moustache with a great speech about men’s health and the importance of getting an annual check-up.

We can also ask for donations to the Movember Foundation, which also has run events all around the world to raise founds for men’s health issues like the prior quoted prostate cancer, depression or testicular cancer. So here we are. Some of us at the Zentyal’s HQ are wearing a terrible moustache, it doesn’t look nice, but we do not care about it; we are proud to explain everyone, including our workmates, why we are wearing this.

Do not worry! It looks better day by day, and you will start recognising yourself after a few days. Now it is your turn. Now you might become the next antenna to spread Movember message, you will notice that you are not walking alone as you would see other Mo Bros around.

Let’s do it!

More info | Movember

A post by Miguel Julián

We have a winning Fluffy picture!

Communication No Comments »

Congrats to @Miripi! The picture of her exclusive, customized Fluffy cube was the most voted by Zentyal staff (we really loved it!). It really seems that the quickest way to win the hearths of Zentyal staff is to wear a heavy t-shirt 😉

As promised, the winner gets a small Zentyal gift package. Miripi, we hope you will enjoy it!

Did you already make your own Fluffy? Not yet? Check out this post where you can find the instructions to make your own Fluffy.

A post by Marta Cambronero

Keep Learning, the Kaizen path

Development  Tagged , , , , No Comments »

I would like to share with you a story that I recently read in this post blog.

The woodcutter story

Once upon a time a very strong woodcutter asked for a job with a timber merchant, and he got it. The salary was really good and so were the work conditions. For that reason, the woodcutter was determined to do his best.
His boss gave him an axe and showed him the area where he was supposed to work. The first day, the woodcutter brought 18 trees. “Congratulations,” the boss said. “Go on that way!” Very motivated by the boss’ words, the woodcutter tried harder the next day, but could bring 15 trees only. The third day he tried even harder, but could bring 10 trees only. Day after day he was bringing less and less trees.

“I must be losing my strength”, the woodcutter thought. He went to the boss and apologized, saying that he could not understand what was going on. “When was the last time you sharpened your axe?” the boss asked. “Sharpen? I had no time to sharpen my axe. I have been very busy trying to cut trees…”

Moral of the story : Working hard is not enough; one has to keep on sharpening one’s skills.

It amaze me when I read it the first time. It makes obvious something that normally when building software we forget, sharpening our axe. Some people will argue that it’s not the same, you don’t use and axe to program Zentyal or any other software. That’s right, it’s even worse. Our tools are more complex, and difficult to master, so things like testing, proper coding, estimation, etc. need more time to be studied and correctly used. The good news are that we, as developers, can do a lot more than sharpening an axe.

One philosophy that fits well with this story and that I really love and try to practice it’s the Japanese Kaizen. It means “continuous improvement” and it came from the Toyota Production System. In software and for me it means that we should trying to improve our process, continually. Never getting satisfied with a particular way of doing the things or the quality that we are delivering. It always can be better without a doubt. Perfection it’s not a state it’s a path.


A post by Julio José García Martín

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