Aliasing is the process of replacing one recipient address with one or more different recipient addresses. The replacement address can be that of a single user, a list of recipients, a program, a file, or any mixture of these.
There is one new aliasing item, but it is not covered until Chapter 23:
Extend the default LDAP specifications for the
AliasFileoption and for file classes to include support for LDAP recursion by way of new attributes (see Section 23.1.2 [V8.13]).
Here, we cover a topic that was only mentioned in a footnote in the third edition.
The name postmaster is required by RFC2822, and all sites must accept mail to that address.[17] RFC2142 takes the concept of postmaster one step further by recognizing that other roles now correspond to well-known email addresses. For example, most web sites that sell products also accept email to the address sales, which is now a well-known email address.
Table 12-1 shows all the newly required addresses
defined by RFC2142. Of these, only postmaster is
treated in a case-insensitive manner by
sendmail.[18] That is, mail to
postmaster, Postmaster,
POSTMASTER, and PoStMaStEr
will all be delivered to the same
person.
Table 12-1. RFC2142-defined email addresses and aliases
|
Address |
RFC |
Description |
|---|---|---|
|
abuse |
RFC2142 |
Accepts reports of unacceptable behavior |
|
ftp |
RFC959 |
Accepts mail reporting ftp needs or problems |
|
hostmaster |
RFC1033 through RFC1035 |
Accepts mail reporting needs or problems with DNS |
|
info |
RFC2142 |
Who replies to requests for information about the business and its products and services |
|
marketing |
RFC2142 |
Handles marketing communications |
|
news |
RFC977 |
A synonym for Usenet |
|
noc |
RFC2142 |
Accepts mail for the network operations center that deals with network infrastructure problems and requests |
|
postmaster |
RFC2821 and RFC2822 |
Accepts mail describing email problems |
|
sales |
RFC2142 |
Replies with product or services information |
|
security |
RFC2142 |
Sends or receives security notices and answers security concerns |
|
support |
RFC2142 |
Accepts mail describing problems with products or services |
|
usenet |
RFC977 |
Accepts email notification of problems with the Usenet News system; (note that abuse should be reported to the abuse address) |
|
uucp |
RFC976 |
For sites that support UUCP, accepts mail describing problems with that service |
|
webmaster |
RFC2068 |
Accepts mail describing problems with or requests for changes in web services |
|
www |
RFC2068 |
A synonym for webmaster |
Each of these required addresses is actually required only if you offer the service indicated in the description (shown in Table 12-1). For example, if you do not run UUCP (as few do), you may safely ignore mail to uucp. If you later add UUCP services, you should add an alias for uucp.
RFC2142, then, suggests that a well-formed aliases file might contain the following entries:
info:recipientmarketing:recipientsales:recipientsupport:recipientabuse:recipientnoc:recipientsecurity:recipientpostmaster:recipienthostmaster:recipientusenet:recipientnews:recipientwebmaster:recipientwww:recipientuucp:recipientftp:recipient
Note that recipient will be a person in
some instances, and in others it will be a program or a file.
In addition to requiring specific recipient addresses, RFC2142 also
requires that mailing lists always have a mailbox that can be reached
using the literal suffix -request. That is, if a
mailing list is named bobs, the administrative address
must be bobs-request.
This behavior is easy to maintain using sendmail
(with the process is covered in 12.1[3ed])
and could be implemented in an aliases file
entry that looks like this:
testlist: :include:/mail/lists/testlist owner-testlist: postmaster testlist-request: bob
Here, the first line defines the actual mailing list as a list of
addresses read from the file
/mail/lists/testlist. The second line defines
the address that should process bounced email generated by this list.
The third line defines the -request address that
will receive administrative email concerning the list.
[17] Some Internet sites (such as spews.org) fear mail to that address because of improper Internet behavior, and improperly reject mail to postmaster. Also, some sites (such as aol.com) reject all mail from residential sites, including mail to postmaster and abuse.
[18] Although RFC2142 requires that they all be treated in a case-insensitive manner.