[CentOS] Mail Send and Receive Problem

Dear Friends ,

I have postfix mail server it is in running condition. But suddenly it is
giving me error *Unknown user or password incorrect.
*
when I check log it is showing me
*"Sep  5 10:26:51 student dovecot: imap-login: Aborted login (auth failed,
1 attempts): user=<jiten at student.ac.in>, method=PLAIN, rip=192.168.1.2,
lip=192.168.1.2, secured"*

After wait for few second it is giving me another log .

Sep  5 10:08:45 student postfix/anvil[9307]: statistics: max connection
rate 1/60s for (smtp:10.200.12.1) at Sep  5 10:05:25
Sep  5 10:08:45 student postfix/anvil[9307]: statistics: max connection
count 1 for (smtp:10.200.12.1) at Sep  5 10:05:25
Sep  5 10:08:45 student postfix/anvil[9307]: statistics: max cache size 1
at Sep  5 10:05:25
Sep  5 10:13:56 student postfix/smtpd[9447]: connect from
mailrly1.student.ac.in[192.168.1.2]
Sep  5 10:13:56 student postfix/smtpd[9447]: warning: restriction
check_sender_mx_access: bad argument
"/etc/postfix/maps/verisign_mx_access": need maptype:mapname
Sep  5 10:13:56 student postfix/smtpd[9447]: NOQUEUE: reject: RCPT from
mailrly1.student.ac.in[192.168.1.2]: 451 4.3.5 Server configuration error;
from=<webmaster at strandbookstall.com> to=<divya at student.ac.in> proto=SMTP
helo=<mailrly1.student.ac.in>
Sep  5 10:13:56 student postfix/cleanup[9451]: 20E2BFA0F54: message-id=<
20120905044356.20E2BFA0F54 at student.student.ac.in>
Sep  5 10:13:56 student postfix/smtpd[9447]: disconnect from
mailrly1.student.ac.in[192.168.1.2]
Sep  5 10:13:56 student postfix/qmgr[9236]: 20E2BFA0F54: from=<
double-bounce at student.student.ac.in>, size=791, nrcpt=1 (queue active)
Sep  5 10:13:56 student postfix/virtual[9452]: 20E2BFA0F54: to=<
postmaster at student.ac.in>, orig_to=<postmaster>, relay=virtual, delay=0.12,
delays=0.06/0/0/0.05, dsn=5.1.1, status=bounced (unknown user: "
postmaster at student.ac.in")
Sep  5 10:13:56 student postfix/bounce[9453]: warning: 20E2BFA0F54:
undeliverable postmaster notification discarded
Sep  5 10:13:56 student postfix/qmgr[9236]: 20E2BFA0F54: removed
Sep  5 10:17:16 student postfix/anvil[9449]: statistics: max connection
rate 1/60s for (smtp:192.168.1.2) at Sep  5 10:13:56
Sep  5 10:17:16 student postfix/anvil[9449]: statistics: max connection
count 1 for (smtp:192.168.1.2) at Sep  5 10:13:56
Sep  5 10:17:16 student postfix/anvil[9449]: statistics: max cache size 1
at Sep  5 10:13:56


I am not understand why It is giving me error and how to solve it. Even I
search on google also but not find any answer there. So Please help me to
solve the problem. ASAP


-- 
Thanks & Regards
Jitendra Jha
+91-7498370550