Because I work on-site, sometimes I add a Outlook contact from the client's Exchange server. If I do that, I can only send e-mail to that person using Exchange, even though I enter what appears to be an SMTP address in that contact's e-mail field. When I try to send a message to that person using an SMTP server, Outlook produces this cryptic error:
Task 'xxx.com - Sending' reported error (0x80070057) : 'Could not complete the operation. One or more parameter values are not valid.'
When I look at the contact's e-mail fields (select the contact's All Fields tab, then choose E-mail fields in the Select from: field), I see that Email Address Type is EX instead of SMTP. I think this means that Outlook would use some Exchange-related protocol to send messages to this contact.
The hack to change Email Address Type is …
- Select the contact's details.
- In the General tab, replace the existing the e-mail address with a string starting with smtp:. For example, replace email@example.com with smtp:firstname.lastname@example.org. Note: you have to type in the new dummy address; if you use a suggestion from Outlook, the address type does not change.
- Select the Properties context menu item of the dummy e-mail address. Outlook should display the E-mail Properties dialog. Note that the E-mail type: field now has a value of SMTP.
- In this dialog, remove the smtp: prefix from the e-mail address.
- Press the OK button and the dialog should close.
- Initially, the Contact's e-mail address does not seem to have changed. If you click on the Display As: field, Outlook corrects the e-mail address.
- Delete the string in the Display As: field and press Enter. Outlook should refresh the Display As: field.
- Save the updated contact.
See also this description.
If you want to find out the address type of all your Contacts, just add the E-mail Address Type column to your list of contacts view.