WooCommerce Email Sending Problems

Bit of info before I start:

• I have a WordPress website that sells products via WooCommerce.
• The email is run through g-suite, not through the server.
• Not all emails are sending to customers, the shop owner is saying.
• I'm a WordPress Designer, not Developer... Haha!

I have a client who is complaining that emails aren't getting received by the customers, but some still are. I have my websites running from UKDedicated (GURU Cloud) but the emails itself runs through g-suite.

I have WP Mail Logging installed and it's saying all the emails on the website are sending out, but they're clearly not, not all of them.

Also, have Easy WP SMTP installed too with the correct settings to use g-suite, but when I go to send emails in the test email part, I'm getting this error but as a designer, I'm not understanding the troubleshooting.

I've raised a support ticket with my server and they've said:

Jake,

I believe you use gmail to send mail from the website, which means all emails are sent directly >from your website to gmail and they do not pass through our servers.

If there is a delivery issue for email send via gmail then you will need to raise this with gmail >themselves, as we have no control over their systems.

I hope this helps clarify

Best regards,

Andy GURU

But, when I've googled about, it says the problem is to do with the server - not WordPress or G-Suite.

Any help into resolving this would be much appreciated - as I'm pretty much really confused about this all.

Many Thanks, Jake.