UUCP Support

The mc configuration technique includes four UUCP options to choose from. They are listed in Table 4-5.

Table 4-5. UUCP support






Section 4.6.5

V8.1 and above

Declare sites for SITECONFIG (obsolete)


Section 4.6.6

V8.1 and above

Local UUCP connections (obsolete)


Section 4.5.8

V8.1 and above

The UUCP relay


Section 4.6.7

V8.1 and above

Individual UUCP-to-network translations

Note that two items in the table are marked as obsolete. This is because all their functions have been moved into the mailertable feature (FEATURE(mailertable)). They are included for backward compatibility with early configuration file versions.

Support for UUCP can be included in your mc file with the MAILER command (Section


This declares six[5] delivery agents and the rules to support them. They are listed in Table 4-6.

Table 4-6. UUCP delivery agents






Section 4.6.1

V8.6 and above

Old-style, all ! form of UUCP


Section 4.6.1

V8.1 and above

Synonym for the above (obsolete)


Section 4.6.2

V8.6 and above

Old-style with multiple recipients


Section 4.6.2

V8.1 and above

Synonym for the above (obsolete)


Section 4.6.3

V8.6 and above

Domain-form headers, old-form envelope


Section 4.6.4

V8.6 and above

Domain-form headers and envelope

If support for SMTP delivery agents is also included prior to UUCP, the last two additional delivery agents are included (uucp-dom and uucp-uudom). Note that smtp must be first for this to happen:


If uucp is first, uucp-dom and uucp-uudom are excluded.

When processing UUCP mail (addresses that contain a ! and those that end in a .UUCP suffix), sendmail routes to those hosts on the basis of the class in which they were found. Hosts that are found in $=U are delivered via uucp-old, hosts in $=Y are delivered via uucp-new, and hosts in $=Z are delivered via uucp-uudom.

The choice of which delivery agent to use for UUCP delivery is under the control of the SITECONFIG mc macro (Section 4.6.6). Which you choose depends on what version of UUCP you are running locally and what version is being run at the other end of the connection. There are far too many variations on UUCP to allow specific recommendations here. In general, you need to choose between a domain form of address (gw@wash.dc.gov) and a UUCP form (wash!gw) and then go with the delivery agent that makes the most sense for you. We recommend that you start with the most domain-correct agent, uucp-dom, and see if it works for you. If not, scale back to uucp-uudom, then to uucp-new, and finally to uucp-old as a last resort.

uucp-old (aka uucp)

If you are running an old version of UUCP, you might have to use this delivery agent. All addresses are turned into the ! form even if they were in domain form:

user     becomes       yourhost!user
user@host.domain     becomes       yourhost!host.domain!user

This delivery agent can deliver to only one recipient at a time, so it can spend a lot of time transmitting duplicate messages. If at all possible, avoid using this delivery agent.

uucp-new (aka suucp)

Newer releases of UUCP can send to multiple recipients at once. If yours is such a release, you can use the uucp-new delivery agent. It is just like uucp-old except that it can perform multiple deliveries.


More modern implementations of UUCP can understand and correctly handle domain-style addresses in headers (although they still require the ! form in the envelope). If yours is such an implementation, you can use the uucp-uudom delivery agent.

At the receiving end, the message mail arrives with the five character "From " line showing the sender address in the ! form. The "From " line reflects the envelope address.


The uucp-dom is the most domain-correct form of the available UUCP delivery agents. All addresses, envelopes, and headers, regardless of whether they began in the ! form, are sent out in domain form. Essentially, this uses UUCP as a transport mechanism, but in all other respects it adheres to the Internet standards.

SITE mc Macro (Obsolete)

UUCP connections are declared inside the SITECONFIG file with the SITE mc macro. That mc macro just takes a list of one or more UUCP hostnames:

SITE(sonya grimble)

Each listed host is added to the class that was defined as the third argument to the SITECONFIG declaration.

SITECONFIG mc Macro (Obsolete)

The SITECONFIG mc macro is obsolete but has been retained for backward compatibility. It has been replaced by the mailertable feature (FEATURE(mailertable)).

The SITECONFIG mc macro is useful for maintaining lists of UUCP connections. There are two types of connections: those connected to the local host and those connected to another host. The first type is declared with SITECONFIG like this:

SITECONFIG(`file',` host',`class ')

Here, file is the name of a file (without the .m4 suffix) that is in the directory cf/siteconfig. That file contains a list of SITE declarations (described earlier). The host is the UUCP node name of the local host. The class is the name (one letter, or multicharacter) of a class that holds the list of UUCP connections. For example:


Here, the file cf/siteconfig/uucp.arpa.m4 contains a list of UUCP hosts directly connected to the machine arpa. This declaration would be used only in the machine arpa’s mc file. The list of UUCP hosts is added to the sendmail class-macro $=U in the first example, and $={MyUUCPclass} in the second.

Some single-character letters are special. The special letters available for local connections are U (for uucp-old), Y (for uucp-new), and Z (for uucp-uudom).

A second form of the SITECONFIG mc macro is used by hosts other than the host with the direct UUCP connections. It is just like the earlier form but with the full canonical name of the host:


This also reads the file uucp.arpa.m4, but instead of causing UUCP connections to be made locally, it forwards them to the host arpa.Berkeley.EDU.

The hostname that is the second argument is assigned to the $W sendmail macro. The class $=W is set aside to hold lists of hosts that appear locally connected. This class is also used with the SITE mc macro. The letters that are available for remote sites are V, W, and X.

If nothing is specified, the class becomes Y. If class U is specified in the third parameter, the second parameter is assumed to be the UUCP name of the local site, rather than the name of a remote site. In this latter case, the specified local name has a .UUCP appended, and the result is added to class w.

Note that SITECONFIG won’t work if you disable UUCP with the nouucp feature (FEATURE(nouucp)).


If your site has a host that used to be a UUCP site but is now on the network, you can intercept and rewrite the old address of that host into the new network address. For example, mail to the machine wash used to be addressed as wash!user. Now, however, wash is on the network, and the mail should be addressed as user@wash.dc.gov.

The UUCPSMTP mc macro provides the means to specify a UUCP-to-network translation for specific hosts. The earlier example would be declared like this:


The UUCPSMTP mc macro should be used only under LOCAL_RULE_3.

[5] Actually, there are only four; uucp and uucp-old are synonyms for the same agents, as are suucp and uucp-new.

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