Add a reaction to a message
POSThttps://api.postpress.ai/v1/messages/{message_id}/reaction
Attach an emoji reaction to a message on WhatsApp or LinkedIn. Sending a new reaction from the same account on the same message replaces the previous one.
Provider support: WhatsApp and LinkedIn only. Other providers return 403.
Authorization
X-API-KEYstringrequired
API key from your postpress dashboard. Sent as a request header.
Path parameters
message_idstringrequired
The id of the message to react to.
Request body
Send as application/json.
reactionstringrequiredNative emoji to react with, e.g. 👍. Provider rules apply (WhatsApp allows any emoji; LinkedIn accepts a fixed set).
{
"reaction": "👍"
}Response 200 OK
objectstringMessageReactionAddedrequiredsuccessbooleanrequiredAlways `true` when the reaction was registered with the provider.
Example request
curl --request POST \
--url 'https://api.postpress.ai/api/v1/messages/msg_01HXYZ4QK3WJ8FN3M6QH7TZ8GR/reaction' \
--header 'X-API-KEY: pp_live_...' \
--header 'content-type: application/json' \
--data '{
"reaction": "👍"
}'Example response
{
"object": "MessageReactionAdded",
"success": true
}Errors
Every error response follows the same envelope:
titlestringrequired
Short error title.
detailstringoptional
Human-readable explanation.
instancestringoptional
Request identifier for support.
typestringrequired
Error type identifier.
statusnumberrequired
HTTP status code.
401 Unauthorized13 types
Credentials are missing, expired, or otherwise invalid.
errors/missing_credentials- Some credentials are necessary to perform the request.errors/multiple_sessions- LinkedIn limits multiple sessions on certain Recruiter accounts. Use the cookie connection method.errors/invalid_checkpoint_solution- The checkpoint resolution did not pass successfully. Retry.errors/invalid_proxy_credentials- The provided proxy credentials are invalid.errors/checkpoint_error- The checkpoint does not appear to be resolvable.errors/invalid_credentials- The provided credentials are invalid.errors/expired_credentials- Credentials have expired. Reconnect the account.errors/insufficient_privileges- This resource is out of your API-key scopes.errors/disconnected_account- The account is disconnected from the provider service.errors/disconnected_feature- The service you're trying to reach is disconnected.errors/invalid_credentials_but_valid_account_imap- IMAP/SMTP credentials are invalid but the account is otherwise valid.errors/expired_link- This link has expired. Generate a new one.errors/wrong_account- The provided credentials do not match the correct account.
403 Forbidden9 types
Authenticated but the account is restricted or the action is not allowed.
errors/account_restricted- The account has been restricted by the provider.errors/account_mismatch- This action cannot be done with your account.errors/insufficient_permissions- Valid authentication but insufficient permissions to perform the request.errors/session_mismatch- Token user id does not match client session id.errors/feature_not_subscribed- The requested feature has not been subscribed or authenticated properly.errors/subscription_required- A subscription is required to use this feature.errors/unknown_authentication_context- An additional step seems necessary to complete login.errors/action_required- An additional step is required.errors/resource_access_restricted- You don't have access to this resource.
500 Internal Server Error3 types
Something went wrong on our side or with the upstream provider.
errors/unexpected_error- Something went wrong.errors/provider_error- The provider is experiencing operational problems. Retry later.errors/authentication_intent_error- The current authentication intent was killed after failure.
503 Service Unavailable5 types
postpress is temporarily unable to handle the request.
errors/no_client_session- No client session is currently running.errors/no_channel- No channel to client session.errors/no_handler- Handler missing for that request.errors/network_down- Network is down on the server side. Retry shortly.errors/service_unavailable- Service temporarily unavailable. Retry later.
504 Gateway Timeout1 types
The upstream provider did not respond in time.
errors/request_timeout- Request timed out. Retry, and contact support if it persists.
Updated May 2026