Each of your Sequences has a Sequence Ruleset you can configure - either one-by-one or by creating a ruleset in Settings > Sequence Rulesets that is then available to apply in one click to any new Sequence you create.
Within every ruleset, there's a Trigger to Mark subsequent emails as failed if anybody in the same account replies that you can turn on or off.
Additionally, you can halt the sending of any more emails to any Contacts in a given Account when you update that Account to any number of Account Stages that you add to the "Mark emails as failed when user sets the account stage of a company to be any of" field.
How To Configure Account Based Settings in a Reusable Sequence Ruleset
1. Navigate to Settings > Sequence Rulesets and click the blue button in the upper right to +Add (or click to edit any existing ruleset) to get to the screen below:
2. Configure your account based settings (in addition to the rest) and be sure to click Save in the upper-right corner
3. You can then apply your saved Ruleset to any new or existing Sequence in your App
How to Edit Account Based Settings for Existing Sequences
1. Navigate to Sequences, click to view any individual Sequence in your list, then click the Settings tab:
2. Either select an existing ruleset with your desired configuration from the Sequence Ruleset dropdown, or configure the account based settings for this just this one sequence using the highlighted fields
3. Click Save in the upper-right corner