SEP sometimes blocking outgoing emails

One user here is constantly having problems with sending emails. (She's learned to BCC herself in everything she sends to ensure that it has gone through). The last few days, she kept trying to send the same group email over and over again and it would never go through. I finally disabled her SEP and the email went through fine. I've since allowed her the option to turned off the mail and outlook auto protect features of Symantec, hoping that'll temporarily solve her issue. How can I stop Symantec from blocking her outgoing emails without turning off any important features? (She's had problems with standard emails too, not just group emails).

Her machine is running SEP Small Business Edition 12.1.4. It's a managed client.