On Tue, Jul 03, 2012 at 01:26:37PM +0000, Dentzer, Daniel wrote:
> E.g. in http://en.wikipedia.org/wiki/Email_address#Specification are some
> more explanations:
>
> "Systems that send mail must be capable of handling outgoing mail
> for all valid addresses. Contrary to the relevant standards, some
> defective systems treat certain legitimate addresses as invalid
> and fail to handle mail to these addresses.
The above text is unjustifiably pejorative. Systems that deal with the
real world outside the standards group are not necessarily "defective".
Postfix is quite capable of handling all the allowed RFC 2821/2822
non-special characters in address localparts. By default, sensible
security precautions and backwards compatibility settings are in
place:
- swap_bangpath = yes
This protects internal systems (Sendmail, Postfix or other)
from becoming multi-hop open relays if they support "host!user"
UUCP address rewriting.
- allow_percent_hack = yes
Much the same, but for "user%internal@external" legacy addresses.
- allow_min_user = no
Protects careless administrators and shell script authors from their
own folly. For example in master.cf pipe(8) argv= specs:
SAFE:
argv=myscript -f ${sender} -- ${recipient}
UNSAFE:
argv=myscript -f${sender} ${recipient}
argv= argv=myscript -f ${sender} ${recipient}
null_sender= argv=myscript -f${sender} -- ${recipient}
Disable these measures at your peril. If your installation is simple
and carefully maintained these are not needed. In practice people
are lazy and sloppy and benefit from the extra care that Postfix
takes to save them from themselves.
--
Viktor.
