On 12/01/2023 13.16, Viktor Dukhovni wrote:
On Thu, Jan 12, 2023 at 12:46:03PM +1300, DL Neil wrote:
That depends on whether you used virtual_alias_maps or alias_maps. Also,
there is a limit on the queue file size (with a name message_size_limit
that would more accurately be message_plus_envelope_size_limit).
If you're asking the question, perhaps you mean to send mail to lists
of O(10k) or O(100k) recipients. If so, you need to do more than just
expand the alias.
No!
I was picking-up such vibes from the earlier discussion.
In particular, you'll surely need an "owner-alias", and it would be
best to snapshot the recipient list into a file, which is used via
the ":include:" mechanism of aliases(5). This gets around all limits
other than queue file size for the post-expansion forwarding hop.
You'll probably want to use "VERP" and ensure that the agent that
sends mail to the list uses it.
Thus, if max-out at a list of ten accounts, and allow for an average
address 50-characters long, only looking at an (ASCII) total of 500B
(actual data)!
If you're serious about *10* recipients, then this thread is a waste of
everyone's attention. Nothing interesting happens until you reach at
least ~1000 recipients, at which point you could start hitting at least
the virtual alias expansion or recursion limits.
Yes, serious about the ten.
Nothing is a waste of attention - at least I am paying attention!
As you say, even a modest server will handle such a small load's effect
on queues, etc.
The original question was about the DB interface.
On the other hand, any time you forward inbound back out to an external
recipient (even just one), you need to worry about SPF, DKIM, DMARC,
your IP reputation and the efficacy of your anti-spam filters, and all
that jazz. The simplest solution is to not redirect inbound mail
outward. Otherwise, you have a bunch of issues of which the recipient
count is the least of your worries.
Bad actors aside. Perhaps I misunderstood earlier contributions to the
previous/primary thread...
Experiment:
- from an external address and server, send a message to the 'list' account
- postfix receives the message
- logs show postfix forwards the message
- two different domains on this server receive successfully
- message also forwarded to two external domain/servers
However, when forwarding externally, postfix doesn't re-transmit with
*my* SPF, DKIM, etc, and therefore receipt will fail or be marked as
spam by competent email services.
Summary:
works for in-house applications, but best not used to forward messages
from outside-sources to external domains.
Thank you both!
--
Regards =dn
