On a heavily loaded machine, I had the following error:

[jbasney@dg-011 ~]$ cat rft.xfer 
true
16000
16000
false
1
true
1
null
null
false
10
gsiftp://dg-011.ncsa.uiuc.edu:2811/etc/group
gsiftp://dg-011.ncsa.uiuc.edu:2811/tmp/rftTest_Done.tmp
[jbasney@dg-011 ~]$ rft -h $HOSTNAME -f rft.xfer
Number of transfers in this request: 1
Subscribed for overall status
Termination time to set: 60 minutes

 Overall status of transfer:
Finished/Active/Failed/Retrying/Pending
0/0/1/0/0
Error:Error authenticating user at source/dest hostServer refused performing
the request. Custom message: Server refused GSSAPI authentication. (error code
1) [Nested exception message:  Custom message: Unexpected reply: 421 Idle
Timeout: closing control connection.] [Caused by: Server refused performing the
request. Custom message: Server refused GSSAPI authentication. (error code 1)
[Nested exception message:  Custom message: Unexpected reply: 421 Idle Timeout:
closing control connection.]]
All Transfers failed !

I had the maximum number of retries set to 10, but RFT didn't appear to retry. 
When I run it again, it succeeds:

[jbasney@dg-011 ~]$ rft -h $HOSTNAME -f rft.xfer
Number of transfers in this request: 1
Subscribed for overall status
Termination time to set: 60 minutes

 Overall status of transfer:
Finished/Active/Failed/Retrying/Pending
0/1/0/0/0

 Overall status of transfer:
Finished/Active/Failed/Retrying/Pending
1/0/0/0/0
All Transfers are completed