Why don't my emails receive responses anymore - whereas they always did in the past

I am a business consultant in the pharma sector. For many years, I could count on the fact that, an email I send would receive a response. Perhaps not always, and if not, it was 50/50 or at worst 4/10. At present, however, many emails are not being read or seen, since I am not getting any responses from those I send to. These people also include close friends, etc., and that’s why I suspect it has something to do with my email system - whatever that means. I have been using GoDaddy for my hosting, and then switched for Google last year. Is there any way to do a “deep-diagnosis”? Thanks to anyone who can help with this?

Hi Reuben,
I’m not sure if I understand correctly what your problem is - are you not sure if your messages are received or that you do not receive your replies?
If you want to be sure your emails are delivered and/or read, I can suggest turning on the Receipts function.
You can set these in Tools > Settings > Mail > Receipts and check Delivery receipts to get a verification that message was delivered and Read receipts where the recipient will be asked to confirm that he has read the message.
Hope this helps.