System Settings - Marketing Campaigns
The Marketing module is a licenced feature of which the settings for external Marketing Campaigns can be enabled via the Marketing Campaigns tree-view node within the System Settings:

API Key: This is an API key which will be provided by Mail Chimp in order to integrate with them.
Contact company / address 1 / town / county / postcode / country: The details of the sender company.
Default from name: Text in this field will auto populate the From name when creating a marketing campaign for MailChimp.
Default from email address: Text in this field will auto populate the From email when creating a marketing campaign for MailChimp.
Default reply to email address: Text in this field will auto populate the Reply to email when creating a marketing campaign for MailChimp.
Permission reminder: Text in this field will auto populate the Permission reminder when creating a marketing campaign for MailChimp. This is a required field, by MailChimp, and tells the recipients of the campaign why they are receiving an email.
Use tags: This setting should be enabled when using a free account version of MailChimp as it only allows one audience list. Using tags allows segments to be used in MailChimp to specify which contacts from the audience list to add to a campaign.
Default list ID: An audience list ID is required when generating campaigns using tags. This setting is only accessible when the 'Use tags' setting above is enabled.

SDK URL: The CommuniGator SDK URL is used to integrate with the Marketing module within OrderWise. It can be found within CommuniGator via Tools > Integration > Security.
Username / Password: Username and Password to log into the CommuniGator account.
Default from name: Text in this field will auto populate the Name when creating a marketing campaign for CommuniGator.
Default from email address: Text in this field will auto populate the From email when creating a marketing campaign for CommuniGator.
Default reply to email address: Text in this field will auto populate the Reply to email when creating a marketing campaign for CommuniGator.
Reset last sync date: Setting the date and time using the drop-down menu and clicking the Reset button will reset the last synchronised date, allowing historic data to be downloaded again. If a specific date is selected, this date will be used or keeping the field blank will reset the dates to nothing, so all the data is re-downloaded. The System Settings will need to be closed and reopened for the date to be reset.
Export account number to contact: When enabled, the customer account number will be exported to the crmCompanyID field within CommuniGator.

Days to look back: This setting determines the number of days to look back when using the 'Refresh campaign results' utility. The setting defaults to -1, meaning all CommuniGator and MailChimp marketing campaigns will be included, regardless of the end date. When set to anything other than -1, the value will be added onto the marketing campaign end date and compared to the current date. If this date falls on or after the current date, these campaigns will be included in the refresh. A value less than -1 cannot be entered.