Filter
Top Products
P800/P802
White Paper, January 2003
59
In case (1) User A will connect using a circuit –switched call in much the same way as User B. A
circuit-switch call will be established from the Interworking Centre (IWC) at the mobile operator to
the modem bank at ISP-A. The P800 Messages application will perform a ‘Get&Send’ operation.
Messages will access the POP server at ISP A and collect waiting messages.
If User A now replies to the message and selected ‘Send Now’ on the P800 whilst connected to
internet, the Messages application will connect to the SMTP server at ISP A, which will in turn
connect to the POP server at ISP B and the message will be transferred.
In Case (2) everything happens as in case (1) except that the connection to the ISP is made
directly from the GSM/GPRS network using TCP/IP networking rather than modems. Because
everything is managed by the mobile operator, the POP and SMTP servers can be made
available.
In case (3) the P800 will be connected to the internet via the GSM/GPRS network and the route
to the servers is over the internet. Most ISPs allow a connection from the internet to the POP
server since access to the POP server is password-controlled. In other words, the firewall at ISP
A will allow the connection from the P800 Messages application to the POP server to be made.
The P800 will therefore be able to collect mail over GPRS.
Sending e-mail requires access to the SMTP server. The ISP will have configured the SMTP
server to behave differently when the user is accessing it from the internet. This is done as a
precaution against it being used to send spam (unwanted e-mail). E-mail send is therefore likely
to fail when connected over GPRS and trying to use the third party ISP settings for SMTP.
Typical configurations include:
•
Block all external access to the SMTP Server
•
SMTP server works provided the sender address is in a domain belonging to the ISP.
• SMTP server works provided the recipient is in a domain belonging to the ISP.
•
SMTP server works only after a successful login has been made to an associated POP
server.
•
SMTP server requires a username and password
There are a number of possible workarounds:
•
Switch to an e-mail service offered by the mobile operator
• Check if the SMTP server can be accessed in ‘Secure Mode’ using a password.
•
Find out if the mobile operator has an SMTP server configured to work where the sender
e-mail address belongs to a different domain.
•
Try checking the mail on the POP server and then sending – some ISPs will allow access
to the SMTP server from a user who has recently successfully logged in to the POP sever
•
Ask the ISP to allow external access from the IP number range used by the mobile
operator’s GPRS service
• Connect to the ISP using CSD or HSCSD when e-mail needs to be sent
E-Mail Fetch and Delete Operation
The P800 is designed to work both as the only means of accessing e-mail and to work together
with a PC which accesses the same e-mail account. It is useful to explain how each case works.
Basic Operation
The P800 Messages application fetches e-mail from the POP server using the COPY method.
This means that each e-mail is copied from the sever and therefore two copies exist, one at the
server and one in the P800 e-mail inbox.
When a message in the P800 inbox is deleted, the P800 will delete it from the server the next
time it connects and does a ‘Get&Send’ operation.