[Dovecot] Questions regarding Dovecot's POP3 implementation

[Dale Gallagher]

Hi all

I'm considering moving over my POP3 service from qmail-pop3d to
Dovecot for the following reasons:

- Support for Maildir++ which I have yet to implement
- Already using Dovecot for IMAP, so makes sense i.t.o Maildir++
- Support for SQL based user authentication

My primary concerns are performance and security.

Before I go down that route of migrating away from qmail-pop3d, I'd
appreciate some answers and feedback on the following.

There is mention of the Maildir filename extension W= for virtual file
size here:

http://wiki.dovecot.org/POP3Server

However, I can't find any MDAs which support writing the filename in
this format. Maildrop seems to support S= only?

If Dovecot is only able to read W= in the filename, I would imagine
that  it might make sense to have an MDA like Maildrop write the
message to disk, replacing all LF with CR+LF and finally write the
filename with identical S= and W= filename extensions included?

Example:

Maildrop replaces all LFs with CR+LF in incoming message.

Maildrop writes message as: 1035478339.27041_118.foo.org,S=1000,W=1000
(where 1000 is the file's RFC822.SIZE)

Then Dovecot doesn't have to calculate virtual message sizes.

I've also found this thread:
http://markmail.org/message/oznf2f7m7hvsxqn6

... which suggests changing mail_get_virtual_size to
mail_get_physical_size in src/pop3/client.c

Would this read the size from S=, or do a stat()?

5. Does anyone use Dovecot pop3 service on thousands of mailboxes and
if so, what specific tweaks / setup do you use?

Thanks
Dale