Domain matching in Internet Explorer
If you use a single set of login credentials (username and password) for multiple sites, you may be able to log into them with a single Login item. If the domain is different (e.g. acme.com, acme.net, acme.biz, etc.) you can use Domain Matching to tell 1Password to treat them as the same.
At this time the Domain Matching feature is only available in the Internet Explorer extension.
If domain is the same but merely has a different subdomain (e.g., mail.google.com, maps.google.com, images.google.com, etc.) 1Password will offer the Login item for use at any of them. You don’t need to use the Domain Matching feature.

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On the IE tab of 1Password preferences, click the Domain Matching button.
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In the Domain Matching dialog box, click the upper Add button.
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In the Domain Name dialog box, type the name of one of the sites, and click the OK button.
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For each of the other domains:
a. In the Domain Matching dialog box, click the lower Add button.
b. In the Domain Name dialog box, type the domain name, and click the OK button.
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When you finish setting up the matching for all the domains you want to equate, click the OK button to close the Domain Matching dialog box.