[Mailman-Users] Is Mailman 2.1 not plushack aware?

Bill Cole mailmanu-20100705 at billmail.scconsult.com
Sun Jun 2 20:45:58 CEST 2013

On 2 Jun 2013, at 11:50, Tanstaafl wrote:

> On 2013-06-01 1:40 PM, Bill Cole wrote:
>> It is altogether always wrong for ANY mail software outside of a 
>> domain
>> to parse the local part of an address in that domain except for a 
>> tiny
>> handful of standard special local parts (e.g. "postmaster").
> On it's own, I agree.
>> The use of '+' as a tag delimiter is widespread but it is not in any
>> sense a "standard" and comes nowhere near universality. There is no
>> way for a Mailman instance to know which domains make "user+tag" and
>> "user" equivalent and which do not, so canonicalizing as you suggest
>> would result in breakage.
> Currently factually and technically correct, But...
> There is no reason that Mailman couldn't be enhanced with a 
> configurable *option* that would allow the domain Admin to *tell* it 
> which character(s) (there was recent talk on the postfix list of 
> postfix being enhanced to allow multiple characters to be defined as 
> this delimiter) were to be used as delimiters.

There's no reason MM *couldn't* be "enhanced" in many ways that it never 
*should* be. It's reasonably well-structured open source Python after 

Beyond a few formally standardized cases, assuming equivalency between 
different address local parts in a foreign domain is wrong in principle 
and bad in practice. Postfix's recipient_delimiter has nothing to do 
with foreign domain addresses, it is only relevant to addresses in 
domains for which Postfix handles delivery. It is also worth noting one 
thing mentioned in that thread: it is trivial to replicate the 
functionality of having multiple delimiter characters with regular 
expression alias maps.

The original poster's difficulty was that MM did not see "user at domain" 
as a valid confirmer of a subscription by "user+tag at domain" but it would 
be profoundly wrong for MM to do so. Making MM recognize multiple tag 
delimiters would multiply the wrongness. The solution for that original 
problem is not in MM, it is for people using tagged addresses to have 
the right mix of tools and presence of mind to send mail using a 
suitable address for each message, i.e. if you subscribe to a MM list as 
"user+tag", you need to confirm the subscription from "user+tag", NOT 

There would be less of a problem with a subscriber-specific setting that 
would allow confirmed subscribers to tell MM that it should treat some 
pattern of tagged addresses as equivalent to their subscribed address. 
That would not address the OP's complaint, but it could help for people 
who are error-prone in how they send mail.

> I would love to see this ability in MM3...

To solve what problem?

I abandoned simple tagging years ago precisely because of would-be mail 
wizards who thought it could be useful to programmatically de-tag my 
addresses, allowing them to intentionally override up my personal and 
domain-level mail handling. In place of the transparent "plus hack" I 
now have slightly more complexity in server config that buys me and my 
users safer tagging while occasionally dropping a wannabe deliverability 
wizard into a blackholed moat of his own digging. The feature you want 
to see in MM3 would probably make it easier for a clueless MM admin to 
do that without bad intent or even thought. There's a certain bofhly 
appeal to that, but I try not to let that side hold sway.

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