[exim] strange problem with smarthosts

Hi, everyone,

I'm trying to build a home MTA with exim 4. I have two 2 ISP accounts,
AAA@ISP1 and BBB@ISP2. I want my Exim server to send mail from
AAA@ISP1 via ISP1, and mail from your BBB@ISP2 via ISP2.

My setting is:

smart_route_isp1:
driver = manualroute
domains = ! +local_domains
transport = remote_smtp_isp1
senders = AAA@ISP1
route_list = * ISP1

smart_route_isp2:
driver = manualroute
domains = ! +local_domains
transport = remote_smtp_isp2
senders = BBB@ISP2
route_list = * ISP2

remote_smtp_isp1:
driver = smtp
hosts_require_auth = *


I tried to send a email from AAA@ISP1 to BBB@ISP2. Exim send the email
to my local /var/mail/. (I also tried other address, such as CCC@ISP3,
and I got the same the results). I haven't tried to send email from
BBB@ISP2 yet. The following is the related parts in exim log.

2006-10-28 00:12:12 1GdUJY-0001dj-3n <= localhost U=XXX P=local S=490
id=1223.fsf@ISP1
2006-10-28 00:12:12 1GdUJY-0001dj-3n ** BBB@ISP2: Unknown user
2006-10-28 00:12:12 1GdUJY-0001dm-55 <= <> R=1GdUJY-0001dj-3n U=mail
P=local S=1254
2006-10-28 00:12:12 1GdUJY-0001dj-3n Completed
2006-10-28 00:12:12 1GdUJY-0001dm-55 => XXX <XXX@localhost>
R=localuser T=local_delivery
2006-10-28 00:12:12 1GdUJY-0001dm-55 Completed


When I use the following settings, I can send email successfully.

smart_route_isp1:
driver = manualroute
domains = ! +local_domains
transport = remote_smtp_isp1
route_list = * ISP1

remote_smtp_isp1:
driver = smtp
hosts_require_auth = *


I found that when "senders = AAA@ISP1" is added, the emails were
always send to local /var/mail and got the previous log info. I think
"senders" means checking the email sender address and, if matched, use
the smartroute. Is there anything I did wrong? Or I missed anything?

Thanks in advance!

Wei-Wei Guo