Companies forget just how many years it took to build up their lists of blocked and allowed senders. Email names can trigger spam alerts, mimic blocked words, and email which should be delivered winds up in a spam folder. Office 365 requires you to troll through volumes of blocked mail to find those “false positives” and validate them – there’s currently no ability to upload your existing blocked and allowed lists, so you’re starting from scratch.
Worse, “ham” emails – which are emails that are user-opted subscriptions to bulk email – are automatically blocked by Office 365 so you will either have a lot of disgruntled users or be permitting unwanted spam while you slowly rebuild your lists. You might want to rethink relying solely on built-in Exchange Online Protection in favor of a more flexible email security solution.
For more information on Barracuda email security for Office 365, visit our corporate site here.