In the contact's profile, you can send manually an email to that contact. If the message has already been sent to that contact, you could use the Resend option. If you do not know if the contact has received the message, consult the Messages section in the contact's profile. The article on the contact's profile explains how to get there and what are the possibilities of this interface.
Requirement
To enable the message sending in the contact's profile, you must check the option in the communication type used for the email to send:
Send an email
Under the Deactivate button, click Send an email:
Then, choose the message to send from the list. When you are ready, click on Send.
Resend an email
In the Messages section, locate the email you want to resend to the contact and, only when you are ready, click Resend:
Results
To see if the message has been sent correctly to the contact, see the Messages section. By clicking on See the message as sent to this contact, you will have a view of the sent content: