I need to send event notification emails from ESP32-CAM board using Arduino E-Mail Client Library (GitHub - mobizt/ESP-Mail-Client: ⚡️Arduino E-Mail Client Library to send, read and get incoming Email notification for ESP32, ESP8266, SAMD21 and Raspberry Pi Pico (RP2040) devices. The library also supported other Arduino devices using Clients interfaces e.g. WiFiClient, EthernetClient, and GSMClient.). I tried a Gmail account, but Google recently changed their security requirements. Gmail requires OAuth 2.0 now, which makes it a bit complicated. Most (all) tutorials, e.g. ESP32 Send Emails using SMTP Server: HTML, Text, Attachments (Arduino IDE) | Random Nerd Tutorials, were written before Google made these changes and no longer work. Are there email providers, for which this tutorial still works?
There are examples that you should follow.
Now you need to use app password for Gmail.
In all SMTP examples, read the comments that already described this how to get app password and how to use it with library.
Library works with all SMTP and IMAP servers that complied with rfc guidelines.