imapsync from postfix-dovecot to ZCS 5

[radhikaV]

Hi,
am new around here and fairly amateur at hacking, would be happy if someone could help me out with our migration issue. We are migrating around 4000 users from a postfix environment to ZCS on a CentOS 5 machine. The users got migrated but trying to use imapsync to get their mailboxes across without knowing passwords is an issue.
I tried the following to migrate mail of "someuser" on xx1.bits-goa.ac.in
after including a master user admin1 in dovecot on that server:

imapsync --buffersize 8192000 --nosyncacls --subscribe --syncinternaldates --host1 xx1.bits-goa.ac.in --user1 someone --authuser
admin1 --passfile1 oldpass  --authmech1 PLAIN --host2 zimbrahost.bits-goa.ac.in --user2  someuser --passfile2 zimpass --ssl2 --port2 993  --noauthmd5

but it still returned an authentication failure on host1.
It returns the error

Error login: [xx1.bits-goa.ac.in] with user [someuser] auth [PLAIN]: 2 NO Authentication failed.

Could someone point out what could be wrong?

regards,
radhika