In a recent decision, the National Labor Relations Board (NLRB) reversed its longstanding rule regarding employee use of corporate email systems for the purpose of union organizing.  The historical rule allowed employers to prohibit the use of its email systems so long as it did so on a non-discriminatory basis.  This is no longer the case.  The NLRB reversed direction last month changing the rule.  The new rule requires employers to allow employees to use corporate email systems to engage in union organizing activities.  The use must be during non-working hours and cannot interfere with workplace discipline or production.  So long as employees stay within these vague boundaries, employers must allow use of email for these purposes. 

It is likely your Company's electronic communications policies do not permit this type of usage.  It might be time for a revision of the policy.  At a minimum, you need to ensure no discipline is issued to an employee for this type of usage even if your Company's policy prohibits such usage.