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Typically distribution lists could be used to 'blast' emails to your brokers or suppliers etc.
How to create a distribution list?
Click on your initials 
icon 
icon at on top right of the main page
The following menu will appear select 'Distribution Lists'
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Click on 
to create a new list.
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Follow steps in the image to rename list and start to add new contacts to distribution list.
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Once contacts are added they auto save and appear as below:
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If you need to remove a contact click the 
on the right of the contact to remove.
How to send emails using the new created list ?
Click on
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to compose a new email. Start to type in the distribution list name and select the newly created list.
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You will now see your email updated with the distribution list you created.
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Now complete body of email and click
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NOTE all contacts in distribution list are defaulted to send as BCC
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