Orderpanel email error

[skysel]

When ordering a domain, email is sent with error.. Log below:

Code:

Apr 22 22:02:28 server postfix/cleanup[16470]: 247C6EAA03: message-id=<20080422200228.247C6EAA03@domain.nl>
Apr 22 22:02:28 server postfix/qmgr[4874]: 247C6EAA03: from=<webmaster@admin.domain.nl>, size=698, nrcpt=1 (queue active)
Apr 22 22:02:28 server postfix/local[16471]: 247C6EAA03: to=<=?UTF-8?B?aW5mb0BIb3N0aW5nLVdvcmtzLm5s?=@domain.nl>, orig_to=<=?UTF-8?B?aW5mb0BIb3N0aW5nLVdvcmtzLm5s?=>, relay=local, delay=1.1, delays=0.64/0.26/0/0.19, dsn=5.1.1, status=bounced (unknown user: "=?utf-8?b?aw5mb0bib3n0aw5nlvdvcmtzlm5s?=")

to=<=?UTF-8?B?aW5mb0BIb3N0aW5nLVdvcmtzLm5s?=@domain.nl>

you see what user it generates (bolded)? I was looking over php pages of orderpanel but could not find anything.. Is this a bug or has anyone had similiar problem?