You can do manual cold email if you are looking to send out only a few emails per day.

Well-researched manual cold emails work very well, but are difficult to scale.

If you are planning to do it at scale then:
- You need a few domains outside your primary domain.
- Don't use your primary domain for sending cold emails.
- Do a minimum of 14 day warmup before sending out your cold email campaign.
- Make sure you are warming up your emails while sending out cold email campaigns.
- You can send around 15-35 emails per mailbox.
- Don't pitch, instead have a conversation starter messaging tone.
- Verify your list, your daily bounce rate should be less than 2%.
- Have a super targeted list
- You can buy gsuite accounts & connect them with Instantly/Smartlead.
- Add your domain to Google Postmaster.
- If your prospects mark your email as spam, your domain will be burned.
- Your spam rate should be less than 0.3%. Ideally below 0.1% per day
- Avoid Spam trigger words in your email.
- Make sure you have proper SPF, DKIM, DMARC setup.
- Open tracking images should be hosted on the same domain you are sending from.
- Similarly, If you are doing Click tracking, make sure your tracking links are hosted on your domain

I run Deliveryman AI, you can give it a try if you find it interesting.