Invoice API fields deprecated on 30 June: the full email
See the exact customer-facing artefact produced from a breaking API change, then inspect why the deadline, mapping and limitations are placed where they are.
This is a representative rendered message using Mergelay’s Banner layout. The company name and destination are fictional; the structure is the thing being demonstrated.
Action required: update Invoice API fields by 30 June
Preheader
Replace two deprecated response fields before the compatibility window closes.
NORTHWIND · PRODUCT UPDATES
Action required
Update your Invoice API integration before 30 June
We are moving Invoice API responses to clearer, nested field names. The legacy customer_id and issued_at fields will remain available until 30 June, then stop being returned.
If your integration reads either field, update the mapping before the deadline. Request URLs, authentication and invoice identifiers are unchanged.
Replace customer_id with customer.id.
Replace issued_at with issuedAt.
Test the new response shape before 30 June.
Open the migration guide
The button represents the draft call to action. In a real Update the reviewer supplies the HTTPS destination, and the email cannot be authorized with a label that has no valid URL.
THE FIFTEEN-MINUTE EDIT
Why each part earns its place
The template is short because every block answers a decision the integration owner has to make. Removing a block should make the message less useful, not merely shorter.
01
Put the deadline in the subject
This change can break an integration, so the date is not marketing urgency. A reader triaging the inbox should understand that action is required before opening the message.
02
Name the old and new fields together
A vague promise of clearer data would force the reader into documentation before they know whether they are affected. The two mappings provide a fast test against their current code.
03
State what remains unchanged
Request URLs, authentication and invoice identifiers are stable. Saying that prevents a field rename from sounding like a full API migration and reduces unnecessary escalation.
04
Use one operational action
The migration guide is the only useful next destination. A pricing link, product tour or unrelated announcement would compete with the task required to avoid interruption.
05
Keep the sender and reason visible
The recipient should recognise the product team and understand why they received an operational email. The brand kit provides the visual wrapper; it does not remove the sender’s legal and audience responsibilities.
THE SOURCE CHECK
Evidence the reviewer must verify before sending
The draft sounds definitive because a migration email has to be usable. That makes source review more important, not less.
Removal date
The merged implementation, rollout configuration or accepted migration plan must support 30 June. A date mentioned only in a ticket comment is not enough to notify customers.
Exact field mapping
Confirm spelling, nesting and casing against the shipped response schema. A polished typo in an API migration is worse than a rough sentence that never leaves review.
Compatibility behaviour
Check that both old and new fields really coexist during the stated window. If the rollout varies by version, region or account, the audience and wording must carry that condition.
Unchanged surfaces
The reassurance about authentication and identifiers is a factual claim. Keep it only when the evidence covers those surfaces; otherwise remove it instead of inferring stability.
Migration destination
Open the CTA as the recipient would. It should resolve without private workspace access and contain the instructions the email promises, including a usable example response.
Affected customer list
Mergelay does not discover API consumers or establish permission to contact them. The sender chooses a list they already own and remains responsible for its accuracy and lawful use.
SAME CHANGE, DIFFERENT JOB
What belongs in email and what belongs elsewhere
Information
Customer email
Internal Slack brief
Deadline
One visible date and the action required before it
Rollout milestones, owner and escalation conditions
Field mapping
Only the public old-to-new names needed for migration
Links to source pull requests, test fixtures and the internal runbook
Risk
The customer consequence if no change is made
Known failure modes, affected cohorts and support guidance
Next action
Open one public migration guide
Verify readiness, contact assigned accounts or escalate a blocker
WHAT THE TOOL CONTRIBUTES
The value is the controlled transformation, not the prose alone
GitHub already contains most of the facts: a removal date in the rollout change, the renamed fields in the schema, compatibility logic in the diff and a documentation link in the pull request. The expensive part is assembling those fragments while the context is still fresh, deciding which claims survive, and creating separate messages without introducing a contradiction between them.
Mergelay keeps those sources attached to one Update, prepares only the selected channels and lets a person edit the exact revision that will be approved. If the subject or body changes after review, the later wording does not inherit the earlier decision. That human boundary is useful precisely because an API deprecation should never be promised as zero-touch communication.
The email is also not the permanent record. The release-note Markdown can live in the company’s own documentation or CMS, while Slack carries the internal rollout context. One source does not mean one universal paragraph; it means the factual release boundary is shared before each audience receives its own explanation.
LIMITS
What this template cannot decide for you
It cannot determine which customers call the deprecated fields. Audience selection comes from the customer system or list the sender already controls.
It cannot make an unsupported deadline safe. The reviewer must reconcile rollout configuration, documentation and the merged implementation before authorizing the message.
It is an operational product update, not a lifecycle campaign. Mergelay does not provide behavioural segmentation, subscription management or an unsubscribe centre.
The fictional Northwind identity is present only to show the complete layout. It is not a customer reference, endorsement or claim of measured conversion performance.
Questions
Can I copy this API deprecation email?
Yes, as a structural starting point. Replace every field, date, URL, sender and audience statement with facts from your own release; do not reuse the example deadline as if it described your product.
Should a breaking change also appear in Slack?
Usually, when support, sales or customer success will answer questions about it. Their brief should include ownership and escalation context that does not belong in the customer email.
Does Mergelay know which customers use the deprecated fields?
No. It prepares release communication from GitHub evidence; it is not product telemetry or a customer data platform. You provide the audience you are already entitled to contact.