Hi,
Same problem for me, it appears on Express Dictate but also on Express Scribe.
One interesting thing is that the problem occurs with some PCs but not for all.
Only difference I saw is relative to network configuration :
Working : Win7 x64 Pro / Workgroup (no domain)
Not Working : Win7 x64 Pro / Domain (Windows 2003 domain controller)
Workaround I've found is installing Express Dictate on the Win7 X64 which is not member of a domain, configuration went fine.
Then I go to --> start menu --> regedit --> export the configuration key (HKCU\Software\NCH Swift Sound\Express\SendTo1)
Finally, I have to import the reg file to the Win7 x64 PC (member of a domain) and then it works !!
However, this procedure doesn't work with the latest version but it's ok with ED 5.24
I don't know why it doesn't work with the latest ED 5.54, only difference I've noticed is in the registry, latest version use HKCU\Software\NCH Software\Express\SendTo1 instead of HKCU\Software\NCH Swift Sound\Express\SendTo1
But if I import the reg key in HKCU\Software\NCH Software\Express\SendTo1, ED ignore it and ask me to create another one and I get back to the awful popup "invalid email address"
'hope it helps NCH Team because I've just buy another ED licence and I can't use the latest version (fortunately I have a ED 5.24 backup)
Regards,