[Mailman-Users] Migration to a new server: recommendations for testing the new Mailman server before changing DNS records; also how to avoid lost/bounced messages during change-over?

[David]

see below

On Mon, Jul 8, 2013 at 6:27 PM, Mark Sapiro <mark at msapiro.net> wrote:

> On 07/08/2013 01:29 PM, David wrote:
> > On Thu, Jul 4, 2013 at 10:49 PM, Mark Sapiro <mark at msapiro.net> wrote:
> >
> >     If the mail server on the new box thinks list domains are in its
> local
> >     delivery space (mydestination in Postfix), you can just send mail
> from
> >     an MUA on the local box configured to deliver via SMTP to the local
> MTA,
> >     and it all should work except that mail from Mailman to local
> addresses
> >     will be delivered to the new box instead of the current live box.
> >
> >
> > The new box has no GUI. The OS is Debian 6.
> > $ uname -r
> > 3.9.3-x86_64-linode33
> >
> > The MUA is:
> > heirloom-mailx
> > $ mailx -V
> > 12.5 6/20/10
> >
> > The MTA is postfix. (For some reason I can't run "postconf -d | grep
> > mail_version" so I'll have to ask the sysadmin later about that. But at
> > the moment, I don't know the postfix version.)
> >
> > Given that info, which settings changes should I make to proceed with
> > the testing plan you described above?
> >
> > So far all I did was:
> > 1. create a ~/.mailrc file with contents:
> >
> > set smtp=localhost
>
>
> If that tells mailx to send via smtp to localhost, that's good.
>
>
> > 2. edit /etc/postfix/main.cf <http://main.cf> and change mydestination
> > to the line below:
> > mydestination = localhost, localhost.localdomain
>
>
> If I understood correctly, this is not what you want. My understanding
> is you have an old (current) box with a domain and an IP and DNS for the
> domain pointing to the IP, and after the switch the domain and IP will
> be those of the new box, but for now, the new box has a different IP.
>
> If this is the case, you should not be making any changes to main.cf
> over what you want after the switch, i.e. it should look like that on
> the old box.
>
> Now, in this configuration, list mail should be delivered locally, so if
> you send mail from the local MUA on the new box to a list address, the
> MUA will deliver it to the local Postfix and that in turn will deliver
> it to the local Mailman.
>
> --
> Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
> San Francisco Bay Area, California    better use your sense - B. Dylan
>

Here's what the sysadmin ended up doing.

First, he added our domain in postfix mydestination but it didn't help so
he did these steps:

1) Added our domain in relay_domains

2) Added the following in in master.cf

mailman unix - n n - - pipe
flags=FR user=list argv=/usr/lib/mailman/bin/postfix-to-mailman.py
${nexthop} ${user}

3) Added our domain in transport
Now we can test using a local MUA (mailx) with SMTP set to localhost.
Without the steps above, it just was not working (i.e., we were not able to
successfully send test messages to the list).

I am posting this follow-up for a few reasons. Primarily, I would
appreciate any feedback that I can pass along to our sysadmin.

And since I really don't understand the overall ramifications of the
changes above, I would enjoy learning something if there are any comments.
For example, I assume we'll have to undo those changes when we go live, and
I always hate to make any last minute changes because of the possibility
that something will stop working as a result of those changes.

Finally, if anyone else needs to try what I'm doing, this info is relevant.