Email Blasts & Mimecast

For those sellers whom have been in the business for 5+ years. Have you noticed an increase in mass email outreach being filtered by services like MSFT, Mimecast, etc? I sense this is much more prevalent than when I began selling and was curious what techniques you find to be effective. This isn't meant as a debate of cold call vs outreach, but the best means you find to mass message prospects.

For example, LinkedIn Helper is a newer technique for me though curious what other tools/tricks folks are using.