RfcComplianceException when To/Cc/Bcc display name contains a comma

Problem/Motivation

MessageBuilder splits To/Cc/Bcc on commas and semicolons with a naive preg_split('/[,;]/', ...). That breaks valid RFC 2822 addresses whose quoted display name contains a comma, for example "John Doe, MPH" <user@example.com>.

This became more visible after Mime Mail started formatting recipient addresses with getDisplayName() (#3388498). Symfony then throws RfcComplianceException (e.g. Email ""John Doe" does not comply with addr-spec of RFC 2822.).

Steps to reproduce

1. Enable amazon_ses as the mail sender (optionally with Mime Mail as formatter, simple_address disabled).
2. Send mail to a user whose display name contains a comma (e.g. John Doe, MPH).
3. Observe RfcComplianceException when building the message.

Proposed resolution

Split mailbox-list headers only on commas/semicolons outside double quotes (same idea as core SymfonyMailer using str_getcsv()), so quoted display names are preserved. Keep support for both , and ; as separators.

Remaining tasks

• Review / commit patch
• Add test coverage for quoted display names with commas

User interface changes

None.

API changes

None (internal parsing only). Optional protected helper if extracted.

Data model changes

None.