PitchFriendly, software that helps you with media outreach, tracked 100,000 pitches sent through its program in 2016.  29 percent were sent on Wednesdays, 16 percent on Mondays and understandably only 1 percent went out on a Sunday.

Just under 28 percent of all pitches are ever opened.  Friday has the best opening odds at 32 percent; Monday is 30 percent. 

PitchFriendly chart on days of the week pitches are sent

Wednesday, which is the most popular day to send, offers the worst chance of getting your pitch read at 23 percent.

Follow-up pitches follow the same open rates as initial pitches.

Smaller media lists offer the best open rates.  User with 30 or fewer media contacts experienced more than a 50% overall open rate.  Lists averaging 162 contacts had less than a 25 percent average open rate.

PitchFriendly was developed by Joel Andren and Paul Denya.  Together they founded PR startup PressFriendly in 2013.

Free demo is here: https://www.pitchfriendly.com/users/sign_up