Description of problem:
SELinux is preventing sendmail from 'write' accesses on the sock_file system_bus_socket.

*****  Plugin catchall (100. confidence) suggests   **************************

If you believe that sendmail should be allowed write access on the system_bus_socket sock_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:
# ausearch -c 'sendmail' --raw | audit2allow -M my-sendmail
# semodule -X 300 -i my-sendmail.pp

Additional Information:
Source Context                system_u:system_r:sendmail_t:s0
Target Context                system_u:object_r:system_dbusd_var_run_t:s0
Target Objects                system_bus_socket [ sock_file ]
Source                        sendmail
Source Path                   sendmail
Port                          <Unknown>
Host                          (removed)
Source RPM Packages           
Target RPM Packages           
Policy RPM                    selinux-policy-3.13.1-283.17.fc27.noarch
Selinux Enabled               True
Policy Type                   targeted
Enforcing Mode                Permissive
Host Name                     (removed)
Platform                      Linux (removed) 4.14.5-300.fc27.x86_64 #1 SMP Mon
                              Dec 11 16:00:36 UTC 2017 x86_64 x86_64
Alert Count                   1
First Seen                    2017-12-14 23:37:03 CST
Last Seen                     2017-12-14 23:37:03 CST
Local ID                      d35f156d-a4ba-4531-ae99-ed164c698872

Raw Audit Messages
type=AVC msg=audit(1513316223.259:645): avc:  denied  { write } for  pid=15806 comm="sendmail" name="system_bus_socket" dev="tmpfs" ino=17179 scontext=system_u:system_r:sendmail_t:s0 tcontext=system_u:object_r:system_dbusd_var_run_t:s0 tclass=sock_file permissive=1


Hash: sendmail,sendmail_t,system_dbusd_var_run_t,sock_file,write

Version-Release number of selected component:
selinux-policy-3.13.1-283.17.fc27.noarch

Additional info:
component:      selinux-policy
reporter:       libreport-2.9.3
hashmarkername: setroubleshoot
kernel:         4.14.5-300.fc27.x86_64
type:           libreport

Potential duplicate: bug 1478735