Does anyone have tips on keeping lifecycle emails out of the spam folder?

What criteria make the algorithms immediately put your email in the spam folder?

1. You use spammy words in either the email content or its subject lines.
2. You turn to shared IP addresses.
3. You send bulk emails without having set up the DNS records.
4. You use purchased contact databases.
5. You send bulk emails without prior warming up your mailbox.
6. Your sender score is low, and the bounce rate is high.
7. You send bulk emails and don't allow readers to opt out.
8. You send emails with images, attachments, and links.

Check our article if you want to know what tips can help you build and maintain email deliverability https://stripo.email/blog/email-deliverability-best-practices-you-should-know/

Generally it’s a good idea to use a different domain for emails. You could use a subdomain for the transactional and another for marketing, or use a new domain completely to keep your main addresses reputation clean.

Assuming your using something like SES, and you’re not abusing the emails going out, I think you should be fine.

I found some great tools for this in the end e.g. lemlist

This is a skill in its own right. If you email to a yahoo, gmail, outlook/hotmail address there are 100's of AI engineers trying to spam folder your emails.

I could write a book on solving this problem. However the easiest single step is to request the readers response. As the AI software filters relaxes with a 3% (about) response rate. Encourage a conversation.

The response email address should be a persons name. [first name]@your domain
The subject and email body content should alternate in the outbound mail. Build three templates and alternate them. You only need two words in the subject, and one sentence in the email body that alternates.

Use this tool often https://mxtoolbox.com/ and watch your reputation.

Gmail can't handle more that 500 outbound a day from your domain.