The Boomtown Rats once sang (Tell Me Why) I Don’t Like Mondays. But I don’t think they were speaking about it from a publisher promotional point of view.

Apparently, they could have been.

According to The Best Time to Send Emails (for Better Sales) a new study by Omnisend, Monday is the worst day to send promotional emails, even worse than Saturday. Their examination of over 2 billion promotional campaigns confirmed that the best day to send promotional email is Thursday, followed by Tuesday.

Here are some other data points from the study:

Send Thursday morning. The optimal time for sending email newsletters—those that contain retail offers—is at 8 a.m., just before the workday starts. Those earned an average open rate of 20.32% and a click-through rate of 7.79%—and even more importantly, an average of eight orders per campaign. Thursday is the best day followed by Tuesday and Wednesday.

If not early in day, send at specific times later. Newsletters sent between 4 p.m. and 5 p.m. have the highest click-through rates and orders. Campaigns sent around 1 p.m. also perform well. “While customers might be ready to open and engage with emails at several points during the day, they are more susceptible to purchase around their typical work schedule,” said Rytis Lauris, CEO and co-founder of Omnisend. Campaigns sent at 10 am have a great open rate (19.83%) but a significantly small number of orders per campaign – 4.66. This might indicate that people may look at an email quickly then but don’t have the time to fully examine it.

Weekend sends are becoming more popular. A woman who runs one of the most popular newsletters to CEOs has said that she found the most success sending Sunday evening. This is a time that this group plans for the week ahead. Omnisend found their lowest unsubscribe rates on Sunday or Monday and their highest click-to-open rates on Saturday. AssociationsNow, one of the best email newsletters that I receive, has just started a “weekend edition.” “This special series of Associations Now Daily News Weekend Editions features good reads on big issues facing associations today," they write. "This weekend, explore the future of learning.”

Strongly consider your subject line. Omnisend backs up a point that I’ve made before. There’s a tendency to finish a newsletter or campaign message and relax a bit, come up quickly with a subject line and send. “The subject line should be the most tested thing in your entire email marketing,” they write. “It should be bold and stand out from the rest in your customers’ inboxes. That’s maybe even more important than the timing.”

Think varied channels. “Make an inventory of your emails that you send manually. Maybe something could be automated and organized as an omni-channel experience? For example, instead of email reminders about the latest sale, you could send an SMS. That would be even more personal and with greater open rate.”

Consider audience age. Saturdays at 10 pm may work for a younger audience; 6 am make work for an older one. We hate to deal in stereotypes, but we also shouldn’t rule out certain times just because a good part of the audience may be open-averse. “Use these stats to your advantage, but use them as one factor in your decision.”

Fridays may be getting more difficult. Fridays now have the highest bounce rates, according to Omnisend. That’s something I notice as well with another newsletter I send here.

Use benchmarks. Benchmarks can be useful to see how your email program compares to industry standards. “They can help establish a baseline for figuring out how and where you can improve,” writes Campaign Monitor. “But we also recommend using your own past results as the benchmark. It’s one of the easiest ways to determine what success looks like for your brand.”

They conclude that the key takeaway from the report is to test, test and test some more.