Need email server aid

Christopher Chan christopher.chan at bradbury.edu.hk
Wed Apr 28 01:31:51 UTC 2010


On Wednesday, April 28, 2010 01:43 AM, Alvin Thompson wrote:
> On 04/26/2010 09:02 PM, Christopher Chan wrote:
>>> 1. HTTP is more reliable than SMTP.
>>
>> Never said that. ...
>
> Technically, you're right. But you certainly very strongly implied, on
> several occasions, that SMTP was *less* reliable than HTTP. Otherwise,
> we wouldn't be having this conversion.

No, I was just pointing out that your supposed reliability can be 
affected by external factors and if time taken was part of the 
reliability, it might not fit.


>
>>> 2. SMTP adds too much "parsing overhead" (his words, not mine) for
>>> sending messages. What! Sending messages is SMTP's *job*, so I imagine
>>> the overhead is acceptable.
>>
>> See above.
>
> <quote who="Christopher Chan">
> Hmm, none of them chose to use an existing protocol like smtp with its
> email parsing overhead.
> </quote>

Well yeah. There is an overhead whether you use smtp, pop or imap as 
opposed to using your own protocol for commands. After using whatever 
protocol, you still have extra work to do to extract the email and strip 
off its headers, check the body for commands before carrying it out. 
With your own protocol, the command comes through IN the tcp session. 
And don't forget the context like you love doing: my specious wireless 
access point assumption.


>
>>> 3. You'll lose mail sent to you if your SMTP server goes down.
>>
>> Like when the device is down long enough for the mta to bounce the email.
>
> Not true:
>
> 1. The backup server will get the mail.
>
> 2. If you for some reason don't have a backup server, It will by default
> take around 5 DAYS or more for the sending mail server to give up. I
> imagine most people can get a mail server up and running in 5 days, even
> if they have to buy and assemble a new computer.
>
> 3. If you for some reason don't have a backup server, AND if you can't
> get the computer up and running in 5 days, the mail isn't lost. It's
> returned to the sender.
>
> 4. If you for some reason don't have a backup server, AND if for some
> reason you don't think you can get your mail server running in 5 days,
> AND you don't want the mail simply to be returned, you can configure the
> sending mail server to never give up.
>
> But I'll concede this point: if you live in an alternate universe where
> Bizarro Superman exists, and Bizzaro Superman destroys your mail server
> and any backup servers, and every time another mail server tries to send
> a message to your server (which Bizzaro Superman already destroyed),
> Bizzaro Superman flies around the planet really fast to turn back time,
> and then finds the sending server and destroys it, then you'll lose mail.

Sorry, you are living in the past. Today, it is 'it depends'. External 
factors chap. A lot of mail servers are configured to bounce within a 
day or even shorter. People already assume email to instantaneous and so 
getting a bounce five days later for whatever reason is no longer 
acceptable.


>
>>> 4. You need a separate MX entry for each client that uses your mail server.
>>
>> Again, Alvin missed the part where Chuck was thinking of embedding a
>> smtp server in the devices for accept remote commands via email. Each
>> device would need either an MX or a host record in DNS.
>
> Not true. http://www.postfix.org/postconf.5.html#transport_maps

/me rotfl. So you expect Chuck's potential customers for his wireless 
remote controlled toy to have to clue to setup a routing for the thing? 
I don't know why you want to throw whatever you can think of at me 
without considering what might be the possible customers of Chuck. I did 
not pass off your report about Lucid trashing data as some freak 
accident or PEBCAS like others did.


>
>>> 5. Spam can still get in your queue if the SMTP server requires a valid
>>> client certificate.
>>
>> Never said that nor did I argue the point of using certificates. If I
>> were to say something, it would be, this is painful for setting up.
>
> <quote who="Christopher Chan">
> Assuming there are no queues due to a bounce flood, due to spam clogging
> the queues and a host of other possible impediments, you expect 40
> different mx/host records to be setup for a roll out involving 40 of
> Chuck's access point?
> </quote>

Right...who requires valid client certificates on their mxs? When you 
find an example, do let me know. And of course, we want to do this so 
that we can remote control a wireless capable toy via email.


>
>>> 6. Mail servers only have one queue.
>>
>> Which is true depending on mta and setup but I never said mail servers
>> only have one queue.
>
> <quote who="Christopher Chan">
> Assuming there are no queues due to a bounce flood, due to spam clogging
> the queues and a host of other possible impediments, you expect 40
> different mx/host records to be setup for a roll out involving 40 of
> Chuck's access point?
> </quote>
>
> At the very least, you have substantial misconceptions on how the queues
> work,if you think a flood of bounces or spam will stop mail from getting
> through.
>

You've never seen mail servers reporting disk full I take it. Of course, 
that is a moot point now. You are right. Using smtp, pop or imap is the 
way to go for remote control of a wireless/wired device. I am amazed 
that nobody has implemented such a great idea. I bow to your 20 years of 
software engineering.




More information about the ubuntu-users mailing list