Email:

A) created a page with region
B) insert Page Items and a button
C) Entered the following code in the PL/SQL page process area.
DECLARE
l_id number;

BEGIN
l_id := APEX_MAIL.SEND(
p_to => :P11_EMAIL,
p_from => :P11_FROM,
p_subj => :P11_SUBJECT,
p_body => :P11_BODY);

COMMIT;
END;

Info With Attahcment
To Apex Mail
More Info

make sense But Need to Test
DECLARE
l_id number;
BEGIN
l_id := APEX_MAIL.SEND(
p_to => 'email@host.com',
p_from => 'email2@host.com',
p_subj => 'TEST',
p_body => 'SOME TEXT HERE',
p_body_html => ' ');
apex_mail.push_queue;
COMMIT;
END;

also note APEX_MAIL.SEND as apposed to htmldb_MAIL.SEND and similar apex_mail.push_queue
and the p_body_html field