Filer loads full letter to work
Sylpheed filter "Options->Filter configuration" fist loads letter with attachments, after that works (!).
Filter works operates only headers of messages. Msg is loaded only if opened.
0) Configure IMAP account in Sylpheed.
1) Configure some filter, for example: "From contains <email@address>" -> "mark as read".
2) Send from appropriate webmail test letter with 20mb attachment.
3.1) Open Sylpheed, some network monitor and see how 20mb is fetched; see to Sylpheed statis bar: it shows same phenomen.
3.2) Select some not loaded yes letter with big attachmens, configure some filter for it. Start filters by hand. See how this message is fetched before be filtered.
OS: Debian Squeeze
Program version: 3.3.0beta1