1SLOCAL(1) General Commands Manual SLOCAL(1)
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6 slocal - asynchronously filter and deliver new mail to nmh
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9 /usr/libexec/nmh/slocal [-help] [-version] [-addr address] [-info data]
10 [-sender sender] [-user username] [-mailbox mbox] [-file file]
11 [-maildelivery deliveryfile] [-verbose | -noverbose] [-suppressdup
12 | -nosuppressdup] [-debug]
13
15 slocal is a program designed to allow you to have your inbound mail
16 processed according to a complex set of selection criteria. You do not
17 normally invoke slocal yourself, rather slocal is invoked on your
18 behalf by your system's Message Transfer Agent (such as sendmail) when
19 the message arrives.
20 The message selection criteria used by slocal is specified in the file
22 “.maildelivery” in the user's home directory. You can specify an
23 alternate file with the -maildelivery file option. The syntax of this
24 file is specified below.
25 The message delivery address and message sender are determined from the
27 Message Transfer Agent envelope information, if possible. Under send‐
28 mail, the sender will obtained from the UUCP “From:” line, if present.
29 The user may override these values with the -addr and -sender switches.
30 The message is normally read from the standard input. The -file switch
32 sets the name of the file from which the message should be read,
33 instead of reading stdin. This is useful when debugging a “.maildeliv‐
34 ery” file.
35 The -user switch tells slocal the name of the user for whom it is
37 delivering mail. It must exist on the local system. The -mailbox
38 switch tells slocal the name of the user's mail drop file.
39 slocal is able to detect and suppress duplicate messages. To enable
41 this, use the option -suppressdup. slocal will keep a database con‐
42 taining the Message-ID's of incoming messages, in order to detect
43 duplicates. Depending on your configuration, this database will be in
44 either ndbm or Berkeley db format.
45 The -info switch may be used to pass an arbitrary argument to sub-pro‐
47 cesses which slocal may invoke on your behalf.
48 The -verbose switch causes slocal to give information on stdout about
50 its progress. The -debug switch produces more verbose debugging output
51 on stderr. These flags are useful when creating and debugging your
52 “.maildelivery” file, as they allow you to see the decisions and
53 actions that slocal is taking, as well as check for syntax errors in
54 your “.maildelivery” file.
55 Message Transfer Agents
57 Most modern MTAs including sendmail, postfix and exim support a .for‐
58 ward file for directing incoming mail. You should include the line
59 “| /usr/libexec/nmh/slocal -user username”
61 in your .forward file in your home directory. This will cause your MTA
63 to invoke slocal on your behalf when a message arrives.
64 The Maildelivery File
66 The “.maildelivery” file controls how slocal filters and delivers
67 incoming mail. Each line of this file consists of five fields, sepa‐
68 rated by whitespace or comma. Since double-quotes are honored, these
69 characters may be included in a single argument by enclosing the entire
70 argument in double-quotes. A double-quote can be included by preceding
71 it with a backslash. Lines beginning with `#' and blank lines are
72 ignored.
73 The format of each line in the “.maildelivery” file is:
75 header pattern action result string
77 header:
79 The name of a header field (such as To, Cc, or From) that is to
80 be searched for a pattern. This is any field in the headers of
81 the message that might be present.
82 The following special fields are also defined:
84 source the out-of-band sender information
86 addr the address that was used to cause delivery to the
88 recipient
89 default this matches only if the message hasn't been delivered
91 yet
92 * this always matches
94 pattern:
96 The sequence of characters to match in the specified header field.
97 Matching is case-insensitive, but does not use regular expres‐
98 sions.
99 action:
101 The action to take to deliver the message. When a message is
102 delivered, a “Delivery-Date: date” header is added which indicates
103 the date and time that message was delivered.
104 destroy
106 This action always succeeds.
107 file, mbox, or >
109 Append the message to the file named by string. The message
110 is appended to the file in mbox (uucp) format. This is the
111 format used by most other mail clients (such as mailx, elm).
112 If the message can be appended to the file, then this action
113 succeeds.
114 mmdf
116 Identical to file, but always appends the message using the
117 MMDF mailbox format.
118 pipe or |
120 Pipe the message as the standard input to the command named by
121 string, using the Bourne shell sh to interpret the string.
122 Prior to giving the string to the shell, it is expanded with
123 the following built-in variables:
124 $(sender) the out-of-band sender information
126 $(address) the address that was used to cause delivery to
128 the recipient
129 $(size) the size of the message in bytes
131 $(reply-to) either the “Reply-To:” or “From:” field of the
133 message
134 $(info) the out-of-band information specified
136 qpipe or ^
138 Similar to pipe, but executes the command directly, after
139 built-in variable expansion, without assistance from the
140 shell. This action can be used to avoid quoting special char‐
141 acters which your shell might interpret.
142 folder or +
144 Store the message in the nmh folder named by string. Cur‐
145 rently this is handled by piping the message to the nmh pro‐
146 gram rcvstore, although this may change in the future.
147 result:
149 Indicates how the action should be performed:
150 A Perform the action. If the action succeeds, then the message
152 is considered delivered.
153 R Perform the action. Regardless of the outcome of the action,
155 the message is not considered delivered.
156 ? Perform the action only if the message has not been delivered.
158 If the action succeeds, then the message is considered deliv‐
159 ered.
160 N Perform the action only if the message has not been delivered
162 and the previous action succeeded. If this action succeeds,
163 then the message is considered delivered.
164 The delivery file is always read completely, so that several
166 matches can be made and several actions can be taken.
167 Security of Delivery Files
169 In order to prevent security problems, the “.maildelivery” file must be
170 owned either by the user or by root, and must be writable only by the
171 owner. If this is not the case, the file is not read.
172 If the “.maildelivery” file cannot be found, or does not perform an
174 action which delivers the message, then slocal will check for a global
175 delivery file at /etc/nmh/maildelivery. This file is read according to
176 the same rules. This file must be owned by root and must be writable
177 only by root.
178 If a global delivery file cannot be found or does not perform an action
180 which delivers the message, then standard delivery to the user's mail
181 drop is performed.
182 Example Delivery File
184 To summarize, here's an example delivery file:
185 #
187 # .maildelivery file for nmh's slocal
188 #
189 # Blank lines and lines beginning with a '#' are ignored
190 #
191 # FIELD PATTERN ACTION RESULT STRING
192 #
193 # File mail with foobar in the “To:” line into file foobar.log
195 To foobar file A foobar.log
196 # Pipe messages from coleman to the program message-archive
198 From coleman pipe A /bin/message-archive
199 # Anything to the “nmh-workers” mailing list is put in
201 # its own folder, if not filed already
202 To nmh-workers folder ? nmh-workers
203 # Anything with Unix in the subject is put into
205 # the file unix-mail
206 Subject unix file A unix-mail
207 # I don't want to read mail from Steve, so destroy it
209 From steve destroy A -
210 # Put anything not matched yet into mailbox
212 default - file ? mailbox
213 # always run rcvtty
215 * - pipe R /usr/libexec/nmh/rcvtty
216 Sub-process environment
218 When a process is invoked, its environment is: the user/group-ids are
219 set to recipient's ids; the working directory is the recipient's home
220 directory; the umask is 0077; the process has no /dev/tty; the standard
221 input is set to the message; the standard output and diagnostic output
222 are set to /dev/null; all other file-descriptors are closed; the envi‐
223 ronment variables $USER, $HOME, $SHELL are set appropriately, and no
224 other environment variables exist.
225 The process is given a certain amount of time to execute. If the
227 process does not exit within this limit, the process will be terminated
228 with extreme prejudice. The amount of time is calculated as ((size /
229 60) + 300) seconds, where size is the number of bytes in the message
230 (with 30 minutes the maximum time allowed).
231 The exit status of the process is consulted in determining the success
233 of the action. An exit status of zero means that the action succeeded.
234 Any other exit status (or abnormal termination) means that the action
235 failed.
236 In order to avoid any time limitations, you might implement a process
238 that began by fork()-ing. The parent would return the appropriate
239 value immediately, and the child could continue on, doing whatever it
240 wanted for as long as it wanted. This approach is somewhat risky if
241 the parent is going to return an exit status of zero. If the parent is
242 going to return a non-zero exit status, then this approach can lead to
243 quicker delivery into your mail drop.
244
246 /etc/nmh/mts.conf nmh mts configuration file
247 $HOME/.maildelivery The file controlling local delivery
248 /etc/nmh/maildelivery Rather than the standard file
249 /var/mail/$USER The default mail drop
250
252 rcvdist(1), rcvpack(1), rcvstore(1), rcvtty(1), mh-format(5)
253
255 `-noverbose'
256 `-nosuppressdup'
257 `-maildelivery' defaults to $HOME/.maildelivery
258 `-mailbox' defaults to /var/mail/$USER
259 `-file' defaults to stdin
260 `-addr' defaults to the current user
261 `-user' defaults to the current user
262 -addr and -user will be set the the user part of the Local-Mailbox pro‐
264 file entry, if set.
265
267 None
268
270 slocal was originally designed to be backward-compatible with the
271 maildelivery facility provided by MMDF-II. Thus, the “.maildelivery”
272 file syntax is somewhat limited. But slocal has been modified and
273 extended, so that is it no longer compatible with MMDF-II.
274 In addition to an exit status of zero, the MMDF values RP_MOK (32) and
276 RP_OK [22m(9) mean that the message has been fully delivered. Any other
277 non-zero exit status, including abnormal termination, is interpreted as
278 the MMDF value RP_MECH [22m(200), which means “use an alternate route”
279 (deliver the message to the mail drop).
280
282 Only two return codes are meaningful, others should be.
283 slocal was originally designed to be backwards-compatible with the
285 maildelivery functionality provided by MMDF-II.
286nmh-1.7.1 2016-05-02 SLOCAL(1)