Sending email newsletters is a routine business practice for more than 80% of large organizations in the US, surpassing standalone (79%), lead nurturing (71%), and transactional (62%) emails, according to an email marketing survey from Clutch (www.clutch.co), a ratings and reviews platform for businesses.

Most organizations send out their newsletter multiple times a week, the survey found, with Monday and Friday, between 9 and 11 a.m., being the most popular periods. However, no universal rule governs when to distribute a newsletter, according to email marketing experts.

"We need to send [emails] when they will be at the top of the inbox. If the email gets buried, it is less likely to be opened and read," said Michael Barber, Founder of barber&hewitt , a strategy and planning firm focused on business-to-business (B2B) organizations.

Nearly 90% of email marketers said that email personalization is important. And most of the marketers (70%), say personalization is a key part of their company's email marketing efforts – more so than segmentation, mobile optimization, and A/B testing.

"Email personalization has become so much more than addressing a subscriber by name," said Kayla Lewkowicz, marketing coordinator at Litmus , a web-based email creation, testing, and analytics platform. "Real personalization places the email communication in context with subscriber needs and delivers a relevant message at the exact time the subscriber needs it.”

The first report in Clutch's email marketing series assessed how to determine which metrics to track based on an organization's overarching goals. In that report, 75% of email marketers said they prioritize subscriber list growth.