How to Build an Email Incident Response Plan Before You Need One

Email incidents don't announce themselves in advance. One morning your sending domain shows up on a blocklist. Someone on the team receives a convincing phishing email that appeared to come from your CEO's address. Your transactional email stops delivering and you don't notice until customers start complaining hours later. The businesses that recover quickly share one characteristic: they had a plan before the incident happened. The ones that scramble — making reactive DNS changes under pressure, guessing at root causes, composing customer notifications from scratch — almost always make things worse before they make them better.

Step 1: Define What Counts as an Incident

Your plan needs a clear definition of what triggers it. Without one, people don't know when to escalate, and slow-moving issues don't get caught until they're serious problems.

Common email incidents worth defining explicitly:

• Delivery failure: Transactional or bulk emails are not being delivered, or there's a sudden unexplained spike in bounce rates
• Blacklisting: Your sending domain or IP appears on a major blocklist (Spamhaus, Barracuda, Microsoft SNDS, etc.)
• Account compromise: Unauthorized access to one or more business email accounts
• Spam complaint spike: Complaint rates exceed your acceptable threshold — a threshold that should be defined in advance and monitored automatically
• Domain spoofing: Your domain is being used to send fraudulent emails to customers or partners — often caught via DMARC reporting
• Provider outage: Your email host is experiencing an outage affecting inbound or outbound mail

Not every hiccup warrants activating a formal incident response. The plan is for situations that require coordinated action from more than one person, or that have potential customer impact.

Step 2: Assign Roles Before an Incident Occurs

In a small team, one person might cover everything. In larger organizations, define these roles in advance and make sure everyone knows what they own:

• Incident owner: Coordinates the response, tracks status, and owns internal and external communication
• Technical responder: Has access to mail server logs, DNS controls, sending platform settings, and can execute configuration changes
• Customer communications: Owns any external messaging to affected customers or partners — only if the incident has public-facing impact

Document primary and backup contacts for each role. Incidents don't wait for the right person to be available.

Step 3: Write Playbooks for Each Incident Type

For each incident category, write a short action sequence — steps the on-call person can follow without having to invent the response under pressure.

Delivery failure playbook

1. Check your sending platform dashboard for error codes and bounce details
2. Determine whether the problem is isolated to one recipient domain or affecting all outbound mail
3. Check whether your sending IP or domain appears on major blocklists
4. Verify that SPF, DKIM, and DMARC records are intact and passing
5. If blocklisted: initiate delisting procedure (document this separately for each major list)
6. If not blocklisted and root cause is unclear: escalate to your email provider with log samples
7. Communicate status to internal stakeholders within your defined SLA window

Account compromise playbook

1. Revoke all active sessions for the affected account immediately
2. Reset the account password and rotate any API keys associated with it
3. Review sent mail in the compromised account for the past 30 days for unauthorized activity
4. Check for forwarding rules, filters, or auto-responders added by the attacker
5. Notify anyone who may have received fraudulent mail from the compromised account
6. File a report with your email provider
7. Conduct a post-incident review to determine how access was gained and prevent recurrence

Domain spoofing / DMARC alert playbook

1. Review your DMARC aggregate reports to identify the sending sources and volume of spoofed mail
2. Confirm your DMARC policy is set to at least p=quarantine — if it's still at p=none, tighten it
3. Identify whether the spoofing is using your exact domain or a lookalike domain — these require different responses
4. If a lookalike domain: report it to the registrar and relevant abuse teams
5. Notify customers who may have received spoofed mail, if volume justifies it

Step 4: Pre-Write Communication Templates

Write your external communication templates before you need them. In the middle of an active incident, composing a careful customer notification from scratch is difficult and slow. Templates just need the specifics filled in:

• A customer notice for when transactional email is delayed (order confirmations, password resets, etc.)
• A notice if your domain has been spoofed and customers may have received fraudulent mail
• An internal alert for staff about a suspected account compromise

Step 5: Secure Access to Critical Systems

Your incident response plan is useless if the person handling the incident can't access the right systems quickly. Document and securely store:

• Login for your email hosting control panel
• Login for your DNS management provider
• Login for your SMTP relay or sending platform
• Your email provider's support contact and ticket portal URL
• Links to blocklist lookup tools and their delisting portals

Store this information in a shared password manager or a secure internal wiki — not in one person's email inbox.

Step 6: Run a Post-Incident Review After Every Event

After each incident, hold a short review: what happened, what the timeline was, what worked, what didn't, and what changes to make. Update the relevant playbook immediately while the details are fresh. The goal isn't assigning blame — it's making the next response faster and more effective.

Track incidents over time. If you're repeatedly getting blacklisted from the same sending segment, that's a systemic signal about list quality or sending practices, not a series of unrelated events. Patterns in your incident log are the most actionable data you have for preventing future problems.

The MailDog support team is available to help diagnose active deliverability incidents, and the documentation covers the configuration issues that come up most frequently. Visit maildog.io to learn more about the infrastructure that keeps your email running reliably.