I am not experiencing the same symptom. My working theory is that there is one email message (maybe more) in your SpamCop Email System Inbox that is causing Webmail to not be able to display the first 50 messages in that Inbox. Is the problem happening with both
https://webmail.spamcop.net/ and
http://webmail.spamcop.net/? Workarounds for accessing the other 49 messages in that Inbox (maybe less) and then forwarding the offending message to JT and taking that message offline include: displaying fewer messages per page (7 then 1 or maybe 16 then 4 then 1); turning off preview; and using another interface to view that Inbox, such as IMAP4 or POP3 (remembering to "leave on server") on local Client software or on another web Client like
mail2web. When using such workarounds, please keep in mind that more email messages may be showing up during your use, and that sort orders may vary in different Clients.