From Discover Card Customer Service
Date Received: 11/09/2011 10:06 AM
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Certain e-mail addresses are set aside for use by more than one individual and do not always provide full security for your personal information. Among these are addresses containing the words "webmaster", "info", "sales" and "spamgourmet." These are automatically blocked to protect your privacy.
Please provide a different e-mail address so that you may continue to receive e-mail alerts and other information.
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Update: 2011-11-21, after trying to explain to them that the username is not shared. They replied with:
Certain e-mail addresses are set aside for use by more than one individual and do not always provide full security for your personal information. Among these are addresses containing the words "webmaster", "info", "spam" and "sales." These words located in either the "user name" or "domain name" location are automatically blocked to protect your privacy.
There are other posts that suggest aliases to "spamgourmet.com"