SELinux is preventing /usr/bin/uux from 'read' accesses on the fifo_file fifo_file.

I believe this happens when postfix passes mail supposed to be sent over UUCP to uux, cf. the changes needed for local delivery to dovecot_t in 3.9.13-6:

...
- Allow dovecot_deliver_t to read/write postfix_master_t:fifo_file. 
        * These fifo_file is passed from postfix_master_t to postfix_local_t to dovecot_deliver_t
...

*****  Plugin leaks (50.5 confidence) suggests  ******************************

If you want to ignore uux trying to read access the fifo_file fifo_file, because you believe it should not need this access.
Then you should report this as a bug.  
You can generate a local policy module to dontaudit this access.
Do
# grep /usr/bin/uux /var/log/audit/audit.log | audit2allow -D -M mypol
# semodule -i mypol.pp

*****  Plugin catchall (50.5 confidence) suggests  ***************************

If you believe that uux should be allowed read access on the fifo_file fifo_file by default.
Then you should report this as a bug.
You can generate a local policy module to allow this access.
Do
allow this access for now by executing:
# grep uux /var/log/audit/audit.log | audit2allow -M mypol
# semodule -i mypol.pp

Additional Information:
Source Context                system_u:system_r:uux_t:s0
Target Context                system_u:system_r:postfix_master_t:s0
Target Objects                fifo_file [ fifo_file ]
Source                        uux
Source Path                   /usr/bin/uux
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           uucp-1.07-25.fc15
Target RPM Packages           
Policy RPM                    selinux-policy-3.9.16-24.fc15
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Enforcing
Host Name                     (removed)
Platform                      Linux (removed) 2.6.38.6-27.fc15.x86_64 #1 SMP Sun
                              May 15 17:23:28 UTC 2011 x86_64 x86_64
Alert Count                   12
First Seen                    Mon 30 May 2011 01:33:54 PM CEST
Last Seen                     Thu 02 Jun 2011 12:31:44 AM CEST
Local ID                      054b7b75-af13-4c81-bfba-1d78d6e75725

Raw Audit Messages
type=AVC msg=audit(1306967504.0:7864): avc:  denied  { read } for  pid=20218 comm="uux" path="pipe:[21477]" dev=pipefs ino=21477 scontext=system_u:system_r:uux_t:s0 tcontext=system_u:system_r:postfix_master_t:s0 tclass=fifo_file


type=AVC msg=audit(1306967504.0:7864): avc:  denied  { write } for  pid=20218 comm="uux" path="pipe:[21477]" dev=pipefs ino=21477 scontext=system_u:system_r:uux_t:s0 tcontext=system_u:system_r:postfix_master_t:s0 tclass=fifo_file


type=SYSCALL msg=audit(1306967504.0:7864): arch=x86_64 syscall=execve success=yes exit=0 a0=7fff24415005 a1=7fdbff4fc7c0 a2=7fdbff4fc8c0 a3=7fff24414e40 items=0 ppid=20217 pid=20218 auid=4294967295 uid=10 gid=14 euid=10 suid=10 fsuid=10 egid=14 sgid=14 fsgid=14 tty=(none) ses=4294967295 comm=uux exe=/usr/bin/uux subj=system_u:system_r:uux_t:s0 key=(null)

Hash: uux,uux_t,postfix_master_t,fifo_file,read

audit2allow

#============= uux_t ==============
allow uux_t postfix_master_t:fifo_file { read write };

audit2allow -R

#============= uux_t ==============
allow uux_t postfix_master_t:fifo_file { read write };