Can a 0.5% reply rate just be...UPDATE

Two weeks ago I posted about my lackluster reply rate after sending 600 cold emails and getting a 0.5% reply rate. Some commented that it wasn't enough time to judge the results, but I knew something was wrong. My original post:

https://www.reddit.com/r/coldemail/comments/1r9blga/can_a_05_reply_rate_just_becold_emailing_is_tough/

Now, here are my results for the last two weeks:

Emails sent: 1,200
Reply rate: 6.14%

I realized something simple: cold email is hard, but my subject lines were the real problem.

I spent tons of time thinking about the tech stack, infrastructure, domains, copy, sequences, everything. But looking back, I basically phoned it in on the subject lines. After all that work, I fed my email copy into CGPT and got subject lines like "Quick introduction". Maybe I was tired or just excited to launch my campaign. I now have subject lines that spark curiosity.

Now I realize: If nobody opens the email, how can they possibly reply? And I wasn't (and am still not) tracking open rates, so the problem was basically invisible to me.

Just wanted to share and thanks for all the replies (I mean from my original post, not my 1200 emails lol).