@Taifun thank you. This is the link I see in a lot of messages, and before I wrote here a little bit I looked at it, but it doesn't seem to me that there is among that list of titles, the one that allows me to reach my goals:
Did you try the example?
For address, use the address slot should prefill.
Use TextBoxes at the green arrows to prefill subject and message.
What is the example I could try? Is there an example from which I can see that I can set address?
I'm sorry but I didn't understand.
Thank you again
Only to understand you: is this the example?
Use a button component together with the camera comoonent
Use one of the solutions mentioned in my previous link, for example my mail extension, which offers adding attachments App Inventor Extensions: Mail | Pura Vida Apps
Use some label or textbox components
Use another button component
A very good way to learn App Inventor is to read the free Inventor's Manual here in the AI2 free online eBook App Inventor 2 Book: Create Your Own Android Apps ... the links are at the bottom of the Web page. The book 'teaches' users how to program with AI2 blocks.
There is a free programming course here Course In A Box and the aia files for the projects in the book are here: App Inventor 2 Book: Create Your Own Android Apps
How to do a lot of basic things with App Inventor are described here: How do you...? .
Also do the tutorials http://appinventor.mit.edu/explore/ai2/tutorials.html to learn the basics of App Inventor, then try something and follow the Top 5 Tips: How to learn App Inventor
Taifun
Trying to push the limits! Snippets, Tutorials and Extensions from Pura Vida Apps by 
Taifun.
Yes, tim's example How do you take a picture and send it to gmail Android client as attachment? - #6 by SteveJG
Thank you @SteveJG , I didn't realize.
I have built this
But I have this error and gmail does not start. What am I doing wrong?
Thank yoi
Are you using these Blocks too?
If you run Tim's example, does it work with a stored png or jpg image?
Possibly you cannot use the SendMailAttach block in the AfterPicture Block immediately?
I have modified my blocks. I have the gmail message that I cand send, but without the attachment.
It's my fault, I have to figure out how to pass the path of the temporary image just taken
The activity starter blocks in @TIMAI2 's example pick an image from shared storage... however your image is stored in ASD amd the activity starter can't pick from there. .
Also as far as I can see @TIMAI2 's extension is not able to send attachments from ASD... @TIMAI2 is this correct?
If you want to use @TIMAI2 's extension then you should copy your image to shared storage and attach it from there
Taifun
Good spot Taifun 
The file in question for the attachment will need to be from Shared Storage otherwise GMail will not be able to find it (and as Taifun says, could not be picked from the ASD using the ActivityStarter in any case)
I have edited my post above top reflect this for others passing here
Hmmm, in testing I cannot get it to attach a file now.....
Got it working, GMail needs a contenturi !
Blocks to follow
There may be an extension that converts a file path to a contenturi, so that you can automate the image file selection.
First of all thank you very much @TIMAI2 !!!
And then I'm kind of glad to see that it's not such a simple thing.
However, I need to find a way not to have the photo selected, but to send the one taken directly.
But don't waste any more of your time.
Thank you very much
well... it can be simple... Here are the blocks using my mail extension
only one button click to take photo and send the email...
after reading again you requirements
your only posibility is to use the activity starter solution (or @TIMAI2 's extension, which is based on the activity starter) to open the client mail app to send the email from there
To avoid picking the file after the image has been copied to shared storage use a file extension to convert the filename to a content uri... my file extension offers the GetUri method for that
Taifun
Okay, good thing you noticed. I was telling you again, that I didn't think your proposal was fair.
I will then evaluate this last extension.
Thank you
???
The question is, why do you have that requirement?
You could have an app specific Gmail account and all users of your app send emails using that account without even knowing user and password of that account. .
Taifun
Because I'm a little crazy and also stupid 
I am joking. Mainly because I want the user to manage it with the best existing email client (and in any case with the one he/she prefers), not with a limited client created by me.
I want the message to not be sent automatically after the shot, but to optionally add anything else after.
And I thought that with MIT you could send a photo you just took to an email client in a more native way, also being able to set pre-filled fields.
