How to document a change to an earlier proposal
Solution 1:
If the description is used as a title or tag in a work-tracking system, you can drop article "the". Where brevity and directness are important, one might change phrases of form "revision of X" to "X revision", and phrases of form "proposal about Y" to "Y proposal". Thus, consider tags like "Proposal revision", "Jones proposal revision", etc.
Unless the proposal is about email, rather than merely transmitted by email, modifying proposal with email is misleading (but emailed would work). For example, "Emailed Jones proposal revision".
Solution 2:
What you've written is grammatical, but could be more clearly expressed by the phrase "revision of the proposal sent previously by email" (with an optional "to fix x, y and z in light of A's comments" if you're feeling expansive and want to indicate why the revision was necessary).