Client implementations compliant with [RFC3501] SHOULD NOT require any
capability name other than "IMAP4rev1". Client implementations
compliant with [RFC9051] SHOULD NOT require any capability name other
than "IMAP4rev2", and possibly "STARTTLS" and "LOGINDISABLED" (on a
cleartext port). All client implementations MUST ignore any unknown
capability names.
The prefix "QUOTA=RES-" is reserved per [RFC9208, Section 9.1].
See Section 9.2 of that document for values that follow this prefix.
All other capabilities starting with the "QUOTA=" prefix are reserved
for future IETF Stream extensions to [RFC9208].
