When you sign up for Remember The Milk, you're assigned a unique email address that allows you to email tasks into your account. The address looks something like:
It's not possible to change this email address, sorry. The "+abc123" part is designed to prevent anyone else from being able to email into your account (unless you tell them the address), and to protect against spam.
If your email software doesn't support addresses that include "+", you might try replacing this sign with "%2b".
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