Has any body else logged in into my account

The following is not a full proof mechanism to find the answer, but it can provide information about last login IP and time of login from that web mail client. Please note that this is visible only one time after login, in MOTD section.
Figure 1.2.2: Last IP and login time information
Image lastip
It is to be noted that the last login IP information is for this web mail client only.