If you want to send an email to a work colleague and guarantee it’s going to be opened, your best bet might be to send it on Sunday afternoon, according to new research from Axios HQ, the communications software company that spun off of Axios.

It analyzed the performance of 8.7 million email deliveries sent through its platform and found that company emails sent from 3 to 6 p.m. on Sunday had the highest average open rate: 94%. (The next highest was Sunday from 6 to 9 p.m., with an open rate of 86%.)

Overall, Sunday and Monday were the best days to get your emails read by coworkers, with an average open rate of 54%. That dips down to 52% on Tuesdays and Wednesdays, then falls on Thursdays and Fridays (to 47% and 49% respectively), before hitting a low of 31% on Saturdays. In general, open rates were also much higher from 3 to 6 a.m. during the workweek (70%) than they were in the afternoon and evening.

Axios HQ suggests that Sundays are a good time to correspond, in part, because you don’t have as much competition in someone’s inbox. But Sunday’s top spot might also be due to the post-pandemic shift to hybrid and flexible work schedules. Rather than sticking to a Monday-to-Friday 9-to-5 schedule, many remote employees are instead opting to catch up on weekends in exchange for going to the gym or attending school functions with their children during traditional workweek hours.

In March, The Wall Street Journal reported that people now work an average of 6.6 hours each weekend, an increase of 5% from 2021, at the height of the pandemic.

However, while working on weekends might seem like a good way to catch from the prior week or to prepare for the one ahead, research from the Academy of Management says otherwise. It found an always-on culture can negatively impact employee health and ultimately hurt job performance rather than help it.

And if you’re a manager, emailing on the weekend might be stressing out your employees. A survey of workers in 2022 found that 63.3% of employees think it should be illegal for employers to contact them outside of working hours; however, almost the same percentage, 64.2%, said they always answer when contacted outside of working hours.

So, while you might get an answer to that Sunday afternoon email, it might be safer to wait to hit “send” until Monday morning.