Trouble in the pipeline

[Craig Routledge <webstuff craigroutledge com>]

Recently, due to a change at my ISP, Balsa has been unable to retrieve  
email via POP.  After examining the datastream and testing with telnet, it  
would seem that the server doesn't like RETRieve commands being sent off in  
quick succession and closes the socket.

Defining POP_SYNC in libbalsa/imap/pop3.c to disable pipelining seems to  
fix things.  However, POP_SYNC only exists in #ifdef's so anyone else with  
one of these servers has to figure this out and recompile.  I also found an  
IMAP_POP_OPT_PIPELINE option, but it doesn't seem to be referenced  
anywhere.  Also, how does Balsa diagnose the problem correctly so that it  
knows when to use the option?  There is no error message, just a dropped  
connection.  And the server claims to support pipelining.

For reference, my only choice in ISPs in my rural location recently  
"upgraded" its mail service and here is the output from the connection:

craig: ~> balsa -d
opening Inbox..
POP S: +OK InterMail POP3 server ready.
POP C: CAPA
POP S: +OK Capability list follows
TOP
USER
RESP_CODES
PIPELINING
EXPIRE NEVER
UIDL
IMPLEMENTATION Openwave Email vM.5.01.06.10.01  
201-253-122-130-110-103-20050629_BCE_UPOP
POP S: .
POP C: User (user hidden)
POP S: +OK please send PASS command
POP C: Pass (passwd hidden)
POP S: +OK mailbox for (email hidden) has 28 message(s)
POP C: List
POP S: +OK 28 message(s)
1 4497
2 4264
3 6883
4 6668
5 4550
6 4039
7 10230
8 4718
9 5927
10 7746
11 6495
12 9483
13 6112
14 5414
15 5059
16 4830
17 4376
18 5091
19 5911
20 5759
21 4165
22 6083
23 10771
24 4350
25 9399
26 4340
27 4009
28 4599
.
POP C: RETR 1
RETR 2
RETR 3
RETR 4
RETR 5
RETR 6
RETR 7
RETR 8
RETR 9
RETR 10
RETR 11
RETR 12
RETR 13
RETR 14
RETR 15
RETR 16
RETR 17
RETR 18
RETR 19
RETR 20
RETR 21
RETR 22
RETR 23
RETR 24
RETR 25
RETR 26
RETR 27
RETR 28
craig: ~>