Standards used in Delta Chat

For everyone, who’s technically interested, here are some of the standards Delta Chat is based on.

Tasks Standards
Transport IMAP v4 (RFC 3501), SMTP (RFC 5321) and Internet Message Format (IMF, RFC 5322)
Embedded media MIME Document Series (RFC 2045, RFC 2046), Content-Disposition Header (RFC 2183), Multipart/Related (RFC 2387)
Identify server folders IMAP LIST Extension (RFC 6154)
Push IMAP IDLE (RFC 2177)
End-to-end encryption Autocrypt Level 1, OpenPGP (RFC 4880) and Security Multiparts for MIME (RFC 1847)
Configuration assistance Autoconfigure and Autodiscover
Messenger functions Email-chat v0.9.0
Detect mailing list List-Id (RFC 2919) and Precedence (RFC 3834)
Send and receive system messages Multipart/Report Media Type (RFC 6522)
Return receipts Message Disposition Notification (MDN, RFC 8098, RFC 3503)

Delta Chat itself is licensed under the GPL license. If you want to know, whether a concrete feature is supported, a look into the source code may help.