utl_smtp - invalid email - code fails - still want to send emails to rest of the people

  We are sending email notifications to all our employees using utl_smtp utility in pl/sql code. Let assume, we are sending email notifications to 1000 employees – which is going great.

Recently we faced a situation where few employees has wrong ( in-valid ) email address in Oracle HR tables. As soon as code ( utl_smtp) tries to send email to invalid address it fails – which is OK. But, code error out ( stop execution) at that point and does not send emails to next employees. We want to send emails to rest of the employees whose email addresses are valid though some of the employees has in-valid email address here & there.(Email validation is not possible for us because we have wide variety of formats).How can we accomplish this