E mail messages stuck in Outbox Outlook 2010 2013 vs Norton Internet
Security
E mail messages stuck in Outbox Outlook 2010 2013 vs Norton Internet Security
Regular solutions for "messages stuck in Outbox" problem at Microsoft: How to troubleshoot e-mail messages that are stuck in your Outbox
But if you use a complex antivirus software, e.g. Norton Internet Security, turn off scanning of outgoing messages: Settings Network Message Protection