## How to reproduce
When an inbound email has malformed sender headers (for example `From:
McDonald <info@example.com` without a closing `>`), mailbox
processing can raise `Mail::Field::IncompleteParseError` while resolving
sender data in `MailPresenter`.
## What changed
This PR hardens sender parsing in `MailPresenter` with a small, readable
implementation:
- Added/used a safe parser (`parse_mail_address`) that rescues
`Mail::Field::ParseError` and `Mail::Field::IncompleteParseError`.
- `sender_name` now uses the same safe parser path.
- `original_sender` now resolves candidates in order via a compact
`filter_map` flow:
- `Reply-To`
- `X-Original-Sender`
- `From`
- All three candidates are parsed as email addresses before use
(including `X-Original-Sender`), and invalid values are ignored.
- `notification_email_from_chatwoot?` now compares sender addresses
case-insensitively (`casecmp?`) to avoid case-only mismatches.
## Test coverage
Added focused presenter specs for:
- malformed `From` header returns nil sender values and does not
classify as notification sender
- malformed `Reply-To` falls back to valid `From`
- valid `X-Original-Sender` is used when present
- invalid `X-Original-Sender` falls back to valid `From`
- mixed-case sender address still matches configured
`MAILER_SENDER_EMAIL`
## How this was tested
Ran:
- `bundle exec rspec spec/presenters/mail_presenter_spec.rb`
- `bundle exec rubocop app/presenters/mail_presenter.rb
spec/presenters/mail_presenter_spec.rb`
Sentry issue:
[CHATWOOT-B9Y](https://chatwoot-p3.sentry.io/issues/7005483640/)
d272a64ff7