## Description
When configuring a From address with a display name (e.g., `Coder System
<system@coder.com>`), the SMTP `MAIL FROM` command was incorrectly
receiving the full address string instead of just the bare email
address, causing `501 Invalid MAIL argument` errors on some SMTP
servers.
## Changes
- Updated `validateFromAddr` to return both:
- `envelopeFrom`: bare email for SMTP `MAIL FROM` command (RFC 5321)
- `headerFrom`: original address with display name for email header (RFC
5322)
Fixes#20727