ipop3d log entry suspicious

[Robert]

Hi,

I'm getting a lot of this entries in the Log under ipop3d section:

Success, while reading line user=appowner
host=customer123-149-157.iplannetworks.net [200.123.149.157]: 1
Time(s)
Success, while reading line user=mysql
host=customer123-149-157.iplannetworks.net [200.123.149.157]: 1
Time(s)
Success, while reading line user=john
host=customer123-149-157.iplannetworks.net [200.123.149.157]: 1
Time(s)

I'm also getting entries like this which I suppose are normal:

Update user=USERNAME host=[LOCAL_IP_ADDR] nmsgs=0 ndele=1: 1 Time(s)

(text in caps refer to real existing users and ip)

Obviously we don´t have any relationship with iplannetworks.net domain
I'm running FC 5.
Didn't find any info on google.

thanks in advance.
Robert.