GetDomains is a procedure used to populate the string list in AStrings with a unique list of domain names found in the Items for the collection. GetDomains clears the contents of the string list in AStrings prior to adding domain names found in the collection. 

GetDomains is useful when performing MX (Mail Exchange) lookups prior to delivery of email messages. 

Use SortByDomain to pre-order items in the collection by their Domain property value. 

Use AddressesByDomain to retrieve a list of email address for a specific domain name. 

Use FillTStrings to populate a TIdStrings instance with the textual version of all email addresses in the collection.

AddressesByDomain 

FillTStrings 

SortByDomain 

TIdEmailAddressItem.Domain