[darcs-users] darcs vs sendmail

Peter Hercek phercek at gmail.com
Fri Mar 13 17:36:20 UTC 2009

Trent W. Buck wrote:
>> If you send it directly to the target mail server you have good
>> change it will accept it.
> Erm, it sounds like you're talking about talking to the server
> example.com directly when darcs wants to address foo at example.com.
> I have a gut feeling that is the Wrong Thing, but I'm not sure why.
It is a cool default since it does not require any setup at all from the 
user. Probably should be combined with sending email to smarthost if the 
smarthost is configured (the options you described a lot and the ones 
you did in your apps).

You do not like it because it is the thing spamers do too. And because 
of spamemrs it is working less and less. The reasons are:
* servers start to check that the domain in hello command exists (which 
mostly would not be a problem) but some even check that the MX record 
corresponds to the sending IP address (probably not that common)
* graylist - the command may not succeed at the first time (server 
claims to be temporary busy even though it is not and does it only 
because the email from the client is coming the first time (error codes 
4xx)); just a retry is required later
* user IP address can be on an RBL list which is used by the destination 
server (if any is used at all; if it is then the server responds with 
permanent error 5xx); this is mostly not a problem for static IPs but if 
an user has a dynamic IP he/she can be on the RBL list because of 
somebody else (who had the address and is running a spam bot)

> My expectation of an in-app SMTP client is that it would send *all* mail
> to a smarthost (e.g. mail for foo at example.com would be sent to
> mail.my-isp.net or mail.my-company.com).
This is what I did not mean, but it is the thing mentioned in 
http://bugs.darcs.net/issue906 and as you described it yourself it 
requires a lot of setup from user.


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