The default shorttag for a contact form is:

[maileon-contact]

1	[maileon-contact]

This tag will display a default form but will most probably not work as expected as it requires some configuration attributes to be set up. Available attributes are the general API configuration attributes from https://maileon.dev/api/rest-api-1-0/contacts/create-contact/ and some plugin specific attributes:

Parameter	Default	Description
permission	1	Specifies the initial permission to be assigned to the contact.Please note: this is the initial permission that is assigned to the contact as soon as it is created. If a double-opt-in process is triggered, the permission is changed to DOI or DOI+ after the contact used the acknowledgement link in the DOI mailing. If the same contact is registered again after already acknowledging the DOI link (and thus, already has Permission 4 or 5) and you call this method with any other permission then 4 or 5 (less valuable), the permission will be ignored, since you already own a valid DOI(+) permission. Further, if Permission 4 or 5 is already set and the account is set up not to send DOI mailings if there is already a DOI permission, no DOI mailing is triggered when creating the contact a second time.Supported values: 1: none 2: single opt-in 3: confirmed opt-in 4: double opt-in 5: double opt-in plus 6: other
sync_mode	2	Specifies the synchronization option in case a contact with the provided email address already exists.Supported values: 1: update (contact data will be updated) 2: ignore (nothing will be done)
src		A string intended to describe the source of the contact. If provided, the string will be stored with the doi process.
subscription_page		In case where this method was called by a subscription page, this string offers the possibility to keep track of it for use in reports.
doi	false	Tells whether a double opt-in process should be started for the created contact. Note that the status code returned for this request does not mean that the doi process succeeded. Supported values are true and false.
doiplus	false	This parameter is ignored if doi is not provided or false. In case the doi process succeeds, Maileon will be allowed to track opens and clicks of the contact.
doimailing		This parameter is ignored if doi is not provided or false. References the doi mailing to be used. If not provided, the default doi mailing will be used.
template		The name of the template file.
standard		JSON map of standard fields and (fixed)values that will be submitted (not visible in form, e.g. a fixed locale,
custom		JSON string of custom fields and (fixed) values that will be submitted (not visible in form.

Explanation for fixed standard and custom fields: You can add a set of standard-/custom-fields with a predefined values, e.g. if you want to submit the German locale for every contact (fixed), you have to provide a JSON object with key-value pairs, where the key is the field name.

For standard fields use the attribute name “standard”, for custom fields“custom”. The keys for standardfields can be found in the API documentation. Be careful to use correct capitalization, also for your custom fields. They must match exactly to the variable names you provided in Maileon.
Example: 

[maileon-contact standard="{'LOCALE':'de_DE'}" doimailing="myDoiKey"]

1	[maileon-contact standard="{'LOCALE':'de_DE'}" doimailing="myDoiKey"]

Please note that by default already existing contacts are not updated to avoid customers overriding information. If you think that updates should be allowed, please pass parameter sync_mode=1.
Example: 

[maileon-contact sync_mode=1]

1	[maileon-contact sync_mode=1]

Also, by default, no DOI mail will be triggered. A good tag to start with would therefore be: