It's July. Have you been sending your e-mails on a Monday?
Perhaps it's worth revisiting the topic: which day of the week results in highest e-mail click through rates? This is of particular importance because studies show that the best day of the week for CTR's varies from month to month.
Check out page 6 of this study.
The author of this paper does point out though that there is no such thing as a universal "best day" to send e-mail. Individual organizations still should conduct their own testing to determine which day of the week works best for them, but any test should consider Friday and Sunday as viable challengers.
Hmmm ... food for thought.