How to Prevent Google Account Disabling When Using Google Apps Script for Daily Marketing Emails?

Question

I am utilizing Google Apps Script (GAS) and Google Sheets to orchestrate daily marketing email campaigns. Despite implementing delays between sending sequences, I've encountered a recurring issue where some of the Google accounts get disabled while others continue to function flawlessly for days. Once disabled, the accounts necessitate phone number verification to restore access, and I've exhausted all my numbers for this verification step.

Here are the steps I've taken to mitigate the account disabling:

1. Incorporated rate limiting and spread out email-sending tasks to avoid hitting any rate limits or triggering automated flags.
2. Ensured compliance with Google's email-sending limits and policies to the best of my understanding.
3. Reviewed the email content to ascertain it aligns with Google's guidelines and isn't getting flagged as spam.

Despite these measures, the problem persists. I am in need of a new phone number for login verification, but more crucially, I aim to understand the root cause of this frequent disabling and seek ways to prevent it going forward.

I'd appreciate any insights, recommendations, or solutions that could help rectify this issue and ensure the smooth operation of the email campaigns using GAS and Google Sheets. Thank you in advance for your assistance.

I initially introduced delays between the email-sending sequences, expecting this would prevent any automated flags or account disabling by not hitting the rate limits set by Google. Despite this measure, some accounts got disabled after a few days of seamless operation, necessitating phone number verification for re-access. I then reviewed and ensured that the email content adhered to Google's guidelines, expecting this would resolve the issue if it was content-related. However, the account disabling issue persisted. Lastly, I ensured compliance with Google's email-sending limits and policies, but still, some accounts get disabled without a clear pattern or reason.

Each time an account gets disabled, I expected to resolve the issue through phone number verification, but now I've exhausted all available numbers for this process. The disabling seems arbitrary and inconsistent, as some accounts continue to operate without any issues while sending a similar volume of emails. The lack of a clear cause or resolution has left me seeking advice and solutions to prevent future account disabling and ensure the smooth operation of my email campaigns through GAS and Google Sheets.