Stupid gmail

Okay not sure what is going on but a few people that I have been sending e-mails too have told me they aren't getting my e-mails. So frustrated, no idea what's going on with my gmail. I'm usually a great e-mail, I don't understand why they aren't going through, either that or it's a big conspiracy on everyone's part to not return my e-mails. Anyway, if you are someone I usually e-mail, please shoot me an e-mail, I have no idea why mine aren't sending