It does, but you can't rely on ARC being implemented by the receiver. ARC is one of the latest additions to email standards (introduced in 2019), there are a l

It does, but you can't rely on ARC being implemented by the receiver. ARC is one of the latest additions to email standards (introduced in 2019), there are a lot of legacy email systems that don't support it. If an SMTP service supports ARC, then it will probably also support DMARC (introduced in 2015) and DKIM (introduced in 2011). So you'll still be better of with using DKIM, as DKIM adds cryptographic proof of authentication and integrity, whereas SPF is just a simple allow list. The big challenge with email is finding a happy medium between security, and backwards compatibility for legacy systems.