Pull mails from an IMAP mailbox and deliver them via SMTP or LMTP

 PullIMAP retrieves messages from an IMAP mailbox and deliver them to an
 SMTP or LMTP transmission channel. Compared to alternatives such as fetchmail
 or getmail, PullIMAP trades flexibility and IMAPd compatibility for
 performance.
 .
 A statefile is used to keep track of the mailbox's UIDVALIDITY and UIDNEXT
 values. While PullIMAP is running, the statefile is also used to keep
 track of UIDs being delivered, which avoids duplicate deliveries in case the
 process is interrupted.
 .
 PullIMAP supports the COMPRESS=DEFLATE extension from [RFC4978]. It is
 enabled by default on servers advertising it in order to reduce network
 traffic, especially for long-lived connections (when IDLE commands are
 enabled.)
 .
 An optional retention period can be set to automatically remove old messages
 from the IMAP server.