Tell me about email.

This is a completely new area for me; networking (outside of I2C or SPI).

I have an uno monitoring my chest freezers, and I would like it to send me an email under 2 occasions:

1: Daily updates of freezer temps. This can be just current temps, not the last 24 hours of monitoring. Just mainly to let me know everything is working. This can be triggered in the setup, as I have the uno set to re-set every 24 hours.
2: In case of over-temp, send me an email alert, in case i'm not home to hear the alarm buzzer.

As I said, totally new to this whole part of the electronics world. i did order 1 of these because they are cheap, small, and I think should do what I need to do.

what are the best guides for me to start learning from?

As I said, totally new to this whole part of the electronics world. i did order 1 of these because they are cheap, small, and I think should do what I need to do.

It depends. If your outgoing email server (usually from your internet provider) supports sending over non-TLS encrypted channels, it's sufficient for your task. But if you want to send it for example over Google's Gmail infrastructure you must use SSL/TLS and this board doesn't support that.

BTW, I2C and SPI is a local bus system and definitely not networking.

Nope, networking is completely new to me, other than running Cat5e to build my home LAN network. I am well past anything resembling knowing what I am doing :smiley:

I have a paid for email service (GoDaddy), I'll see if it can be configured to use those settings, and give my 'duinos a dedicated email address (could be handy in the future for incomings?).

Is there another module that is similarly small/cheap that CAN be used over gmail?

But otherwise, where/what is the best guide to start reading on how to get email messages/networking my 'duinos up and going?

give my 'duinos a dedicated email address (could be handy in the future for incomings?).

I doubt that you will need this. Receiving emails is much more complicated than sending them.

Is there another module that is similarly small/cheap that CAN be used over gmail?

An ESP8266 should do the job quite well.

But otherwise, where/what is the best guide to start reading on how to get email messages/networking my 'duinos up and going?

I don't know, the topic is quite broad and I doubt there is a site explaining everything at beginners level.