Multaple email notifications to the same email address

Hi, I'm asking for help on a project I want to build. Using email notification I want 10 switches each to send a different preset subject line to the same email address no body text is required.
I am using a WiFi R3 ATmega2560 and I just don't know where to start.
I would be very grateful for any help with this. Kind regards David

Can you tell us about your project ? Give us a broader view.
Is it always at the same location (connected to the same home network) ?

Please give a link to your board. There are a few boards that combine ATmega2560 with Wifi.

For sending an email, a ESP32 can be used: https://randomnerdtutorials.com/esp32-send-email-smtp-server-arduino-ide/.

To send an email, you need a SMTP server to send the email to. That can be a problem. My own internet provider had a open SMTP server in the past that I could use with Arduino. Today, almost nothing is possible. The spam filters check a number of things and it is hard with an Arduino to comply with that checklist.
Beside that, some providers require that a user logs in at the website now and then.

Arduino is for learning programming and electronics. Do you think that you can make it yourself ? I'm not writing the sketch, sorry.

If it isn't at the same location every time (WiFi network), then you would need to setup your router for port forwarding. Port forwarding is quite risky though, making it easier for hackers to access your network.

I found that out the hard way. I wrote up a whole code for emailing with google, just to find out that google was blocking them, labelling them as spam. It wasn't obvious either. I spent over an hour trying to figure out why I would not receive an email.

Google definitely won't work. I haven't tested iCloud, or yahoo, or such.

The ESP32 has plenty of I/O pins for 10 buttons. Any reason you chose the Atmega2560 with WiFi (which is quite unusual)?

RandomNerdTutorials has several tutorials for sending emails with ESP32.

Hope this helps.