It's not. The biggest problem is big email providers such like Gmail.
You can't easily run your own mail server because the hurdles you have to overcome to not land in gmails (outlook, etc.) spam folder - or even get delivered at all. DKIM, SPOF, a good IP range.
Then your server itself will be exposed to spam and might make it a lot less fun to use.
The big ones are not playing nice with smaller ones because of spam.
Google, Microsoft really are the destroyers of the internet.
1. Deprecate the 7-bit stuff and make UTF-8 the default codepage.
2. Give up the practice of overquoting (including full text of previous messages into each message - clear message ID and relation tracking is enough).
4. Ban antivirus etc software signatures - misleading statements saying "the message has been checked by an antivirus".
5. Standardize the way inline pictures are attached.
6. Stop prepending countless prefixes like Re:Fwd:RE: in the subject line
7. Give up the practice of discouraging subject specification omission - this leads to uninformative, irrelevant and misleading subject fields in many cases when subject changes, is not clearly defined from the beginning or is hard to describe concisely
8. Standardize supported HTML&CSS subsets.
9. Add support for MarkDown, AsciiDoc or some other lightweight markup.
10. Disallow quoting an forwarding of decrypted versions of previously encrypted content by default.
Many of those "antivirus companies" are selling usage data that they obtain via pixel tracking. Explaining this to someone who uses such "antivirus" is like explaining the difference between the web and the internet, those users don't want to understand the difference.