What’s the difference between local vs remote bounce handling?

Local bounce handling addresses failures within your own infrastructure:

Your mail server detects problems before external transmission. Issues like invalid sender syntax, configuration errors, or internal routing failures. Typically faster to detect and resolve. No external DSN needed because failure is internal.

Remote bounce handling processes failures from external servers:

Your message left your system and reached external servers. External server rejected or bounced the message. You receive a DSN from the remote system. Requires parsing external bounce formats and codes.

Key differences:

Timing: Local is immediate; remote can be delayed. Visibility: Local errors you control; remote depends on external server behavior. Standardization: Remote bounces vary widely in format and detail.

Local bounces are problems in your harbor. Remote bounces are rejections from distant ports.