Comment by AndrewPGameDev

I tried implementing this logic in java with a try-catch style:

        try {
            Validation validation = validate();
            try {
                Value value = update_db(validation);
                send_email(value);
            } catch (DBError db) {
                try {
                    sleep(5);
                    Value value = update_db(validation);
                    send_email(value);
                } catch(InterruptedException ie) {
                    // do nothing, stupid java-ism
                } catch(DBError db2) {
                    try {
                        Value value = update_db_remote(validation);
                        send_email(value);
                    } catch (DBError db3) {
                        notify_user(db3);
                    } catch (EmailFailedError e) {
                        requeue_email(e);
                    }
                } catch (EmailFailedError e) {
                    requeue_email(e);
                }
            } catch (EmailFailedError e) {
                requeue_email(e);
            }
        } catch(ValidationError v) {
            notify_user(v);
        }

https://gist.github.com/Andrewp2/9d97bd213b061166d6df565ce26...

IMHO this is much worse than the railway version you gave, but maybe someone could write a superior version that still uses try-catch.