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jors
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Backup MX exchange

Wed Oct 30, 2013 4:35 pm

Hi there, I am running my own server with the Raspberry Pi and would like to find someone to do a backup MX exchange.

What does "backup MX" means? It means you have a primary mail server (the one it receives mail for a given domain and delivers it to final recipients) and if for any reason it goes down, another mail server (the backup MX) will take care of mail sent to you by keeping it in mail queue for some time (instead of returning it) waiting for your primary to come back online to proceed to their delivery.

Does any Raspberry Pi user have a personal MTA and would like to do this backup MX exchange? BTW, I only have a single mail domain to backup, but no problem if someone has more :)

Cheers.
Blog @ http://enchufado.com/

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DougieLawson
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Re: Backup MX exchange

Wed Oct 30, 2013 8:02 pm

MX is a mail exchanger. You need that if you want to relay email to the rest of the world and have the rest of the world relay your email to you. That's a special record in your domain name system (DNS) to define what server handles email for your domain. A backup MX is what server stores email when your server isn't online (so it can forward it when your system comes back alive).

My ISP does all of that stuff for me (including eliminating the spam), I don't want to run that on my RPi. If I want to send email then I talk to mailhost.ifb.net port 25 or I'll connect to Google's secure mail server. If I want to receive email I'll connect to gmail.com.

So we can apply Mr Cooper's Law.
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jors
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Re: Backup MX exchange

Fri Nov 01, 2013 12:39 pm

I am sorry but I don't get your point. I already know what MX, DNS/DNS records and backup MX are. Maybe it is my fault because I did not make myself clear (english is not my mother tongue, sorry for that). So let me try to explain again my proposal.

I run my personal MTA on the Raspberry Pi (yes, I want to do that) for a domain and I am searching another person that has the same scenario to do that backup MX exchange. The idea is making my Raspberry act as MX for my domain (part already done) + backup MX for someone's other domain/s, and the other person will to the same with his/her Raspberry (act as MX for his/her domain/s + backup MX for my domain).

Let's hope Mr Cooper will be ok with that this time ;)

Cheers.
Blog @ http://enchufado.com/

marchello
Posts: 81
Joined: Fri Oct 11, 2013 8:59 am

Re: Backup MX exchange

Fri Sep 12, 2014 2:12 pm

jors wrote:I am sorry but I don't get your point. I already know what MX, DNS/DNS records and backup MX are. Maybe it is my fault because I did not make myself clear (english is not my mother tongue, sorry for that). So let me try to explain again my proposal.

I run my personal MTA on the Raspberry Pi (yes, I want to do that) for a domain and I am searching another person that has the same scenario to do that backup MX exchange. The idea is making my Raspberry act as MX for my domain (part already done) + backup MX for someone's other domain/s, and the other person will to the same with his/her Raspberry (act as MX for his/her domain/s + backup MX for my domain).

Let's hope Mr Cooper will be ok with that this time ;)

Cheers.
Hi, I found your old post and would like to say that I thought about this too. But I don't like idea of mx exchange. I would rather run another my own raspberry pi as mx backup in other building using other ISP. How about that?

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DougieLawson
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Re: Backup MX exchange

Fri Sep 12, 2014 9:30 pm

It can work.

Open port 25
Update your DNS records to define a backup MX record
Shoot your normal MX server dead so that mail routes to the backup
Sit back and watch the spam flood in to your backup MX server

In general opening port 25 to the public internet is an irresponsible thing to do unless a) you know what you're doing b) you have some strong firewall rules to avoid being a spambot c) have a reliable spam black list and d) you've got enough space and CPU spare to deal with the blacklisted items and, more so, with the greylist items that need to be scored/filtered for their spammyness. Remember the signal to noise ratio with email is remarkably low (80% spam, 20% whitelisted email) and having your ISP filter things before it comes down your wire saves your expensive bandwidth.

Letting the nice people at your ISP do that stuff for you is usually more satisfying. Even letting Dr Google analyse your email so he can send you targeted adverts and, in return, will apply his spam rules is preferable to running it yourself (IMHO).
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FLYFISH TECHNOLOGIES
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Re: Backup MX exchange

Sat Sep 13, 2014 1:51 pm

Hi,
marchello wrote:I would rather run another my own raspberry pi as mx backup
One info that might save some of your time to do other things:
When you have a single mail server and it is down within some interval (some hours), the mails sent to this server / related domain during this time are not lost. The delivery will be retried for several days and if your server is up again, these mails will be delivered.

During this downtime a sender gets related notification (or more of them if downtime lasts a couple of days or so) that the mail has not yet been delivered and that retries will still be performed.

If your mail server is down for several days (depends on setting on each mail server trying to deliver the mail during time time, but 8 days is probably widely used default timeout), then the mail is thrown away + a sender is notified that the mail has not been delivered and the server gave up.

Conclusion: when the downtime occurs here and there for few hours (and you're not professionally in business to provide email services - definitely not, because we're talking about RasPis ;-) ), there is no need to establish this backup "infrastructure".


Best wishes, Ivan Zilic.
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