Mailbox connectivity

I have a user who is dialling in via VPN on his laptop which is running Win98.  He can connect to the network OK, but can't pick up his mail from the Exchange Server 5.5(unavailable).  He can ping the sever OK and I have replicated him in the office and his mail loads fine.  Any ideas?
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What is in front of him? Broadband cable/dsl, or dialup with modem?
bobseeAuthor Commented:
he is connecting via dsl
MTU issue. Especially with DSL. pppoe adds extra overhead in addition to the VPN that creates fragmentation.
What VPN Client? Use DrTCP to adjust the workstation MTU to 1400

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