E-mail is, fundamentally, a text-only application. Non-plain-text data can be sent via that channel by encoding it into a text representation. Plain text has no concept of "font", "color", or "size".

I think you are asking the wrong question, or making incorrect associations.

When I send an e-mail message, I have no control, nor any reasonable expectation of influence over the specific type face, size, or color that the message will apepar in on the recipient's screen. If it is important to specify those parameters as a part of the content you are sending, you have to use a non-plain-text part in a multipart MIME message.

If you are constructing a text/plain part, you may presume that the recipient will view it in a fixed font. If they choose to use a proportional font, the table will be all messed up, but they should be able to deal with that. If their e-mail program won't let them control the font and inflicts a proportional font on them, they need to get a non-broken reader.

So, to get to your question: Not that I know of. Just format the text with blanks on the assumption that it will be viewed in a fixed font.