What is AVIF
Based on the AV1 standard, the AVIF format is an image format. With the AVIF format, you can compress images without sacrificing quality (lossless compression). The AVIF extension is .avif. AOM created AVIF to improve compression efficiency and deliver more features than other formats. The AVIF codec is compatible with high dynamic range images. As well as capturing full-color photos, it can produce images up to ten times smaller than other formats. AVIF is transforming the industry. Eventually, it will likely be incorporated into all platforms because of its potential.
What is Fastmail
Fastmail is an email service provider with a security focus. You will not find any advertisements here at all, as opposed to other email services such as Gmail. However, even for individuals, there is no free version of the service. There are separate offerings for Fastmail business accounts, including the option of setting up a custom domain. Fastmail, which Opera formerly owned, has operated independently since 2013. Fastmail Pty Ltd. provides the service from Australia, but its main servers are located in New York and Amsterdam.
AVIF support
At this time, Fastmail does not support viewing or sending AVIF images inline. As with any other file, you may attach them.