Engadget Guide Details Fixes for iPhone iMessage 'Not Delivered' Error

Engadget said the most popular of those services is iMessage, identified by blue bubbles. It is proprietary to Apple and works automatically when a user messages someone with an iPhone, iPad or Mac. The other two protocols are RCS and SMS, shown as green bubbles. They are built into the Messages app and also work when messaging Android users. The guide said this distinction matters because the service being used can be the reason a message is not sending.

The first workaround Engadget described is to tap the red exclamation point next to a failed message. That action gives the option to try sending the message again. Poor signal coverage can cause the failure: iMessage and RCS rely on an internet connection, while regular SMS requires cellular reception. Engadget said toggling airplane mode on and then off can sometimes help an iPhone reconnect to the cellular network.

If a user has cellular reception but no internet access, the guide said sending the message as an SMS improves the chances of delivery. To do this, the user can tap and hold the failed message and select Send as Text Message. The blue bubble becomes green and is sent over the cell network without Wi-Fi or 5G. Engadget added that users can enable Retry as Text Message under Settings, Apps, Messages. With that option on, the iPhone automatically resends messages as SMS when iMessage or RCS fails.

Engadget also recommended checking that iMessage is enabled. Although it should not happen, iMessage can fail to activate when a user switches to a new iPhone. In the Messages settings, users should look for the iMessage toggle and make sure it is turned on. If trouble continues, the guide suggested disabling iMessage, waiting a minute and turning it back on to refresh the connection to Apple's servers. Users should also check the Send & Receive section to confirm that the correct phone number or email address is selected.

Other external factors can prevent messages from being delivered, according to Engadget. iMessage may go down because of instability on Apple's servers, though the report described that as rare. Users can check Apple's System Status page for performance issues. Engadget also said turning on the MMS Messaging toggle in Messages settings can help prevent problems. Without MMS, users cannot send photos or videos through regular text messages to Android users unless those users have RCS enabled.

The guide said rebooting an iPhone is always a good step when trouble occurs. It also suggested trying to send a message to a different contact. If a message will not deliver to only one person, that person's phone may have no connection, may be turned off, or may have blocked the sender's number.

Finally, Engadget said users should ensure their iPhone is updated to the latest version of iOS, because older software that is not maintained is more likely to have trouble with online services. In the Settings app, users can go to General and then Software Update. If an update is available, they should download and install it. If an iPhone no longer receives software updates, the guide said it might be a good time to consider the Apple Upgrade plan.