By default, send uses the program post to do the actual delivery of the messages, although this can be changed by defining the postproc profile component. Most of the features attributed to send are actually performed by post.

By default the draft is scanned for a header named Nmh-Attachment. The draft is converted to a MIME message if one or more matches are found. This conversion occurs before all other processing. The header name can be changed with the -attach option. This behavior can be disabled completely with the -noattach option.

The first part of the MIME message is the draft body if that body contains any non-blank characters. The body of each header field whose name matches the header-field-name is interpreted as a file name, and each file named is included as a separate part in the MIME message.

For file names with dot suffixes, the profile is scanned for a mhshow-suffix- entry for that suffix. The content-type for the part is taken from that profile entry if a match is found. If a match is not found in the user profile, the mhn.defaults profile is scanned next. If no match is found or the file does not have a dot suffix, the content-type is text/plain if the file contains only ASCII characters or application/octet-stream if it contains characters outside of the ASCII range. See mhshow(1) for more details and example syntax.

Each part contains a name attribute that is the last component of the path name. A x-unix-mode attribute containing the file mode accompanies each part. Finally, a description attribute is generated by running the file command on the file.

The -attachformat option specifies the MIME header field formats: a value of 0 includes the x-unix-mode attribute as noted above. A value of 1, the default, suppresses that, puts the file name in the ``Content-Description'' header, and adds a ``Content-Disposition'' header. A value of 2 adds the file modification-date parameter to the ``Content-Disposition'' header. You can specify one value in your profile, and override it for individual messages at the whatnow prompt.

Here are example message part headers, for an attachment, for each of the -attachformat values:

-attachformat 0:
Content-Type: text/plain; name="VERSION"; x-unix-mode="0644";
        charset="us-ascii"
Content-Description: ASCII text 
-attachformat 1:
Content-Type: text/plain; name="VERSION"; charset="us-ascii"
Content-Description: VERSION
Content-Disposition: attachment; filename="VERSION"
-attachformat 2:
Content-Type: text/plain; name="VERSION"; charset="us-ascii"
Content-Description: VERSION
Content-Disposition: attachment; filename="VERSION"; modification-date="Mon, 19 Dec 2005 22:39:51 -0600"

If -push is specified, send will detach itself from the user's terminal and perform its actions in the background. If push'd and the draft can't be sent, then an error message will be sent (using the mailproc) back to the user. If -forward is given, then a copy of the draft will be attached to this failure notice. Using -push differs from putting send in the background because the output is trapped and analyzed by nmh.

If -verbose is specified, send will indicate the interactions occurring with the transport system, prior to actual delivery. If -watch is specified send will monitor the delivery of local and network mail. Hence, by specifying both switches, a large detail of information can be gathered about each step of the message's entry into the transport system.

The -draftfolder +folder and -draftmessage msg switches invoke the nmh draft folder facility. This is an advanced (and highly useful) feature. Consult the mh-draft(5) man page for more information.

If -split is specified, send will split the draft into one or more partial messages prior to sending. This makes use of the MIME features in nmh. Note however that if send is invoked under dist, then this switch is ignored -- it makes no sense to redistribute a message in this fashion. Sometimes you want send to pause after posting a partial message. This is usually the case when you are running sendmail and expect to generate a lot of partial messages. The argument to -split tells it how long to pause between postings.

Send with no file argument will query whether the draft is the intended file, whereas -draft will suppress this question. Once the transport system has successfully accepted custody of the message, the file will be renamed with a site-dependent prefix (usually a comma), which allows it to be retrieved until the next draft message is sent. If there are errors in the formatting of the message, send will abort with a (hopefully) helpful error message.

If a ``Bcc:'' field is encountered, its addresses will be used for delivery, and the ``Bcc:'' field will be removed from the message sent to sighted recipients. The blind recipients will receive an entirely new message with a minimal set of headers. Included in the body of the message will be a copy of the message sent to the sighted recipients.

If a ``Dcc:'' field is encountered, its addresses will be used for delivery, and the ``Dcc:'' field will be removed from the message. The blind recipients will receive the same message sent to the sighted recipients. *WARNING* Recipients listed in the ``Dcc:'' field receive no explicit indication that they have received a ``blind copy''. This can cause blind recipients to inadvertently reply to all of the sighted recipients of the original message, revealing that they received a blind copy. On the other hand, since a normal reply to a message sent via a ``Bcc:'' field will generate a reply only to the sender of the original message, it takes extra effort in most mailers to reply to the included message, and so would usually only be done deliberately, rather than by accident.

If -filter filterfile is specified, then this copy is filtered (re-formatted) by mhl prior to being sent to the blind recipients. Alternately, if you specify the -mime switch, then send will use the MIME rules for encapsulation.

Prior to sending the message, the ``Date: now'' field will be appended to the headers in the message. If -msgid is specified, then a ``Message-ID:'' field will also be added to the message.

If send is re-distributing a message (when invoked by dist), then ``Resent-'' will be prepended to each of these fields: ``From:'', ``Date:'', and ``Message-ID:''.

A ``From:'' field is required for all outgoing messages. Multiple addresses are permitted in the ``From:'' field, but a ``Sender:'' field is required in this case. Otherwise a ``Sender:'' field is optional.

If a message with multiple ``From:'' addresses does NOT include a ``Sender:'' field but does include an ``Envelope-From:'' field, the ``Envelope-From:'' field will be used to construct a ``Sender:'' field.

When using SMTP for mail submission, the envelope-from used for the SMTP transaction is derived from the ``Envelope-From:'' field. If no ``Envelope-From:'' field is present, the ``Sender:'' field is used. If neither the ``Envelope-From:'' nor the ``Sender:'' field is present, the ``From:'' field is used. When ``Envelope-From:'' appears in a message it will be removed from the final outgoing message.

By using the -format switch, each of the entries in the ``To:'' and ``cc:'' fields will be replaced with ``standard'' format entries. This standard format is designed to be usable by all of the message handlers on the various systems around the Internet. If -noformat is given, then headers are output exactly as they appear in the message draft.

If an ``Fcc: folder'' is encountered, the message will be copied to the specified folder for the sender in the format in which it will appear to any non-Bcc receivers of the message. That is, it will have the appended fields and field reformatting. The ``Fcc:'' fields will be removed from all outgoing copies of the message.

By using the -width columns switch, the user can direct send as to how long it should make header lines containing addresses.

If nmh is using the SMTP MTA, the -server and the -port switches can be used to override the default mail server (defined by the /etc/nmh/mts.conf servers entry). The -snoop switch can be used to view the SMTP transaction. (Beware that the SMTP transaction may contain authentication information either in plaintext or easily decoded base64.)

If nmh has been compiled with SASL support, the -sasl and -nosasl switches will enable and disable the use of SASL authentication with the SMTP MTA. Depending on the SASL mechanism used, this may require an additional password prompt from the user (but the ``.netrc'' file can be used to store this password). -saslmech switch can be used to select a particular SASL mechanism, and the the -user switch can be used to select a authorization userid to provide to SASL other than the default.

If SASL authentication is successful, nmh will attempt to negotiate a security layer for session encryption. Encrypted data is labelled with `(encrypted)' and `(decrypted)' when viewing the SMTP transaction with the -snoop switch. The -saslmaxssf switch can be used to select the maximum value of the Security Strength Factor. This is an integer value and the exact meaning of this value depends on the underlying SASL mechanism. A value of 0 disables encryption.

If nmh has been compiled with TLS support, the -tls and -notls switches will require and disable the negotiation of TLS support when connecting to the SMTP MTA. Encrypted data is labelled with `(tls-encrypted)' and `(tls-decrypted)' when viewing the SMTP transction with the -snoop switch.

The files specified by the profile entry ``Aliasfile:'' and any additional alias files given by the -alias aliasfile switch will be read (more than one file, each preceded by -alias, can be named). See mh-alias(5) for more information.