Feature summary (what you would like to be able to do and where):
I would like to see email adress right in the form so that I can visually check the email address every time. If not entirely, then at least partially, hiding part of the letters with asterisks, leaving only the beginning visible. In the settings, I can see the email address, why can't I see it here...
Make the warning text super visible - a sentence in its own separate paragraph with a contrasting (not gray) background and maybe even framed.
Make a button to check which email address will be specified in the sent email. The new button will be harder for local projects to hide or distort its purpose .
Even the function of postponing sending would be a little useful when, after sending, you remember to really check the email address in the settings of the additional account you have logged into now.
Make one design of this part and guaranteed one user experience with this part for everyone on all sites.

Use case(s) (list the steps that you performed to discover that problem, and describe the actual underlying problem which you want to solve. Do not describe only a solution):
Wikipedia does not prohibit having many accounts. Different accounts may have different email addresses. A participant, in one period of time, can have one main account and other additional ones. Usually, serious attention is paid only to the settings of the main account. Often a participant does not remember the settings of other accounts or can specify a more personal email so that messages do not go unnoticed, but does not attach serious importance to these settings. But the need to use the mail sending form may occur on all accounts.

When using the wikimail form, the account name is shown twice in From: and in Subject:, which lulls vigilance and makes you think that you checked everything before sending. The text about the address is briefly recalled somewhere in the depth of the paragraph with the text and the text is muffled by a gray background, as if it contains unimportant information, just an ordinary help and not a warning, on which it is difficult to read the words - it is so important why it is in the paragraph together with other text, equating to the importance of that text, and not in its own paragraph.

There is so much written in the Terms of Use/Privacy policy about the care and protection of participants and in the wiki there are ways to hide and suppress revisions with personal data. But here the system covertly discloses personal data and this action can no longer be hidden from the addressee of the letter and the participant is helpless to protect himself from disclosure the email address or personal details from the address, it is not guaranteed in any way how the addressee will act with this information.

Please protect the participants from careless disclosure of the email address, protect the participants from themselves and from the insidiousness of the sending form. Do not give away the design of such an important thing for free change in each project. Separate this important part from other messages. Other information about the participant can be found at the email address, or the email address may directly contain personal data - this is very sensitive information.

Benefits (why should this be implemented?):
The site will do its job to protect the privacy of users. The rules will work. Users will feel the care and protection of their data. Users will not get a bad experience from working with the mail sending form.

https://ru.wikipedia.org/wiki/Служебная:Письмо_участнику/Badguy666?uselang=ru