I send periodic mails to my site members but I think that either they are not reaching to them or getting lost in spam folder. How an I know how many mails are indeed being read by my site members ?
1. avoic BCC mails 2. avoid lots of addresses in mails best ONE to for each mail - hence use a mail client that processes the address db one by one like regular individual mail 3. add a hotlinked pic - photo or whatever - if nothing else then a gif grafic or so even as small as 1x1 px that allows you to see how many and which IP downloaded the image 4. include substantial incentives that attract your recipients to go to a page and act like reconfirm membership else membership deleted etc 5. make sure you have a properly configured mail SERVER with max restrictive spf record 6. bypass mail / newsletters by using RSS to keep active site members updated
This is what I do. I place a 1x1 image on the bottom of my newsletters. Then check my stats to get a open rate estimate.