On iOS and iPadOS, third-party developers can extend iMessage capabilities with custom extensions, an example being quick sharing of recently played songs.

On February 16, 2012, Apple announced that a new Messages app replacing iChat would be part of OS X Mountain Lion.

[13] On March 21, 2016, a group of researchers from Johns Hopkins University published a report in which they demonstrated that an attacker in possession of iMessage ciphertexts could potentially decrypt photos and videos that had been sent via the service.

[17] At the WWDC 2020 keynote on June 22, 2020, Apple previewed the next version of its macOS operating system, planned for release in late 2020.

[26][27] Bloomberg speculated that this "tentative" decision was reached because while iMessage's userbase is large enough to qualify, the service is not popular enough with businesses, specifically.

[28] This rumored tentative decision was later formalized on February 13, 2024, when the European Commission announced that they had decided that, together with Bing, Edge and Microsoft Advertising, iMessage does not qualify as gatekeeper services.

[29] The European Commission did not go into detail on their decision beyond stating that it was the result of "a thorough assessment of all arguments, taking into account input by relevant stakeholders, and after hearing the Digital Markets Advisory Committee.

[39] With the launch of iOS 15.2, Apple added automated blurring of photos containing explicit images that are sent to underage users.

The feature relies on scanning the photos on the device and can optionally be set to alert the underage user's parents if explicit material is received.

[47][48] On December 5, 2023, an independent app called Beeper Mini, which used reverse engineering of the iMessage protocol, was released for Android.

[50][51] Amy Klobuchar and Mike Lee, who lead the Senate's antitrust committee, wrote a letter to the Department of Justice expressing concern that Apple was not allowing competition.

Ultimately, the creators of Beeper Mini gave up on bypassing Apple's attempts to shut down the service, so they stopped trying to reverse engineer iMessage.

[54] On November 12, 2012, Chetan Sharma, a technology and strategy consulting firm, published the US Mobile Data Market Update Q3 2012, noting the decline of text messaging in the United States, and suggested the decline may be attributed to Americans using alternative free messaging services such as iMessage.

[56] On November 4, 2014, the Electronic Frontier Foundation (EFF) listed iMessage on its "Secure Messaging Scorecard", giving it a score of 5 out of 7 points.

[57] In September 2015, Matthew Green noted that, because iMessage does not display key fingerprints for out-of-band verification, users are unable to verify that a man-in-the-middle attack has not occurred.

In 2021, an FBI document obtained by Property of the People, Inc., a 501(c)(3) nonprofit organization, through an FOIA request, reveals, that WhatsApp and iMessage are vulnerable to law-enforcement real-time searches.

Migicovsky argues that it is hypocritical of Apple to claim iMessage is private and secure while simultaneously allowing only SMS messages when communicating with users on non-Apple devices (such as Android), even when alternatives exist.

"[66] All four of the security and privacy risks suggested by Apple's statement also apply to SMS, which iMessage uses for fallback when communicating with non-iMessage users.

[67][68][69] Apple has long-resisted bringing iMessage to non-Apple devices, with CEO Tim Cook previously offering the solution of "buy your mom an iPhone" when questioned at Code Conference about a better way to message with family that uses Android.

Massachusetts Senator Elizabeth Warren commented on the conflict between Beeper Mini and Apple, tweeting: "Green bubble texts are less secure.

[72] Claims have been made that the app's use of different colors for messages using iMessage's protocol vs SMS fallback has contributed to social exclusion among some teens.

[77] After the news broke, Google revealed that they will be working alongside Apple to implement RCS onto iOS and iMessage.