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DMA(8) System Manager's Manual DMA(8)


dmaDragonFly Mail Agent


dma [-DiOt] [-Amode] [-bmode] [-f sender] [-L tag] [-ooption] [-r sender] [-q[arg]] [recipient ...]


dma is a small Mail Transport Agent (MTA), designed for home and office use. It accepts mails from locally installed Mail User Agents (MUA) and delivers the mails either locally or to a remote destination. Remote delivery includes several features like TLS/SSL support and SMTP authentication.

dma is not intended as a replacement for real, big MTAs like sendmail(8) or postfix(1). Consequently, dma does not listen on port 25 for incoming connections.

The options are as follows:

acts as a compatibility option for sendmail.
List all mails currently stored in the mail queue.
Queue the mail, but don't attempt to deliver it. See also the ‘DEFER’ config file setting below.

All other modes are are ignored.

Don't run in the background. Useful for debugging.
Set sender address (envelope-from) to sender. This overrides the value of the EMAIL environment variable, but is overridden by the ‘MASQUERADE’ config file setting.
Ignore dots alone on lines by themselves in incoming messages. This should be set if you are reading data from a file.
Set the identifier used in syslog messages to the supplied tag. This is a compatibility option for sendmail.
This is a compatibility option for sendmail.
Specifying -oi is synonymous to -i. All other options are ignored.
Process saved messages in the queue. The argument is optional and ignored.
Same as -f.
Obtain recipient addresses from the message header. dma will parse the To:, Cc:, and Bcc: headers. The Bcc: header will be removed independent of whether -t is specified or not.


dma can be configured with two config files:

  • auth.conf
  • dma.conf

These two files are stored per default in /etc/dma.


Every file contains parameters of the form ‘name value’. Lines containing boolean values are set to ‘NO’ if the line is commented and to ‘YES’ if the line is uncommented. Empty lines or lines beginning with a ‘#’ are ignored. Parameter names and their values are case sensitive.



SMTP authentication can be configured in auth.conf. Each line has the format “user|smarthost:password”.


Most of the behaviour of dma can be configured in dma.conf.

If you want to send outgoing mails via a smarthost, set this variable to your smarthosts address.
(numeric, default=25)
Use this port to deliver remote emails. Only useful together with the ‘SMARTHOST’ option, because dma will deliver all mails to this port, regardless of whether a smarthost is set or not.
(string, default=/etc/aliases)
Path to the local aliases file. Just stick with the default. The aliases file is of the format
nam: dest1 dest2 ...
In this case, mails to nam will instead be delivered to dest1 and dest2, which in turn could be entries in /etc/aliases. The special name ‘*’ can be used to create a catch-all alias, which gets used if no other matching alias is found. Use the catch-all alias only if you don't want any local mail to be delivered.
(string, default=/var/spool/dma)
Path to dma's spool directory. Just stick with the default.
(string, default=not set)
Path to the ‘auth.conf’ file.
(boolean, default=commented)
Uncomment if you want TLS/SSL secured transfer.
(boolean, default=commented)
Uncomment if you want to use STARTTLS. Only useful together with ‘SECURETRANS’.
Pin the server certificate by specifying its SHA256 fingerprint. Only makes sense if you use a smarthost.
(boolean, default=commented)
Uncomment if you want to allow the STARTTLS negotiation to fail. Most useful when dma is used without a smarthost, delivering remote messages directly to the outside mail exchangers; in opportunistic TLS mode, the connection will be encrypted if the remote server supports STARTTLS, but an unencrypted delivery will still be made if the negotiation fails. Only useful together with ‘SECURETRANS’ and ‘STARTTLS’.
(string, default=empty)
Path to your SSL certificate file.
(boolean, default=commented)
Uncomment this entry and change it to ‘INSECURE’ to use plain text SMTP login over an insecure connection. You have to rename this variable manually to prevent that you send your password accidentally over an insecure connection.
(boolean, default=commented)
Uncomment if you want that dma defers your mail. You have to flush your mail queue manually with the -q option. This option is handy if you are behind a dialup line.
(boolean, default=commented)
Uncomment if you want the bounce message to include the complete original message, not just the headers.
(string, default=empty)
The internet hostname dma uses to identify the host. If not set or empty, the result of gethostname(3) is used. If ‘MAILNAME’ is an absolute path to a file, the first line of this file will be used as the hostname.
(string, default=empty)
Masquerade the envelope-from addresses with this address/hostname. Use this setting if mails are not accepted by destination mail servers because your sender domain is invalid. This setting overrides the -f flag and the EMAIL environment variable.

If ‘MASQUERADE’ does not contain a @ sign, the string is interpreted as a host name. For example, setting ‘MASQUERADE’ to ‘john@’ on host ‘hamlet’ will send all mails as ‘john@hamlet’; setting it to ‘percolator’ will send all mails as ‘Sm off username @percolator’.

Bypass aliases and local delivery, and instead forward all mails to the defined ‘SMARTHOST’. ‘NULLCLIENT’ requires ‘SMARTHOST’ to be set.

Environment variables

The behavior of dma can be influenced by some environment variables.

Used to set the sender address (envelope-from). Use a plain address, in the form of This value will be overridden when the ‘MASQUERADE’ config file setting or the -f flag is used.


mailaddr(7), mailwrapper(8), sendmail(8)

J. B. Postel, Simple Mail Transfer Protocol, RFC 821.

J. Myers, SMTP Service Extension for Authentication, RFC 2554.

P. Hoffman, SMTP Service Extension for Secure SMTP over TLS, RFC 2487.


The dma utility first appeared in DragonFly 1.11.


dma was written by Matthias Schmidt <> and Simon Schubert <>.

February 13, 2014 Debian