How to share an address list by emailing the list to a colleague

I'm not sure what you mean by "my address list" so I'll assume it's an address book such as Personal Address Book. Does the other person use Thunderbird? If so, I would export each address book that I wanted to share to its own LDIF file, and send the LDIF files as attachments. If they use some other email software, then a CSV file would likely be more useful. Same process but choose CSV when exporting. If they can use the vCard format then the MoreFunctionsForAddressBook add-on will let you export your Contacts to a file or multiple files which again you send as attachments. To find Thunderbird's export feature, open the Address Book, select an address book, go to Tools in the menu and look for Export.