An issue may be observed when using the eMail.Recipients.AddAddress(string) function in Email Manager scripts when MAPI is being used as the connection method to the mail server.
On customising an Email Manager script, additional recipient addresses can be added to an outbound email by using the eMail.Recipients.AddAddress function.
On inspecting a received email which has been modified by this function, email addresses in the To: field are duplicated.
Each call to AddAddress results in the previous entries in the recipients list being duplicated, i.e. if you call it 3 times, the first recipient will appear 4 times, the second 3 times, the third twice, and the fourth once.
Similar behaviour is seen when adding CC and BCC addresses, so these don't work as a workaround.
Use SMTP / POP3 with Exchange. If a secure connection (SSL/TLS) is required, then you can use stunnel. A KBA is available (492-16235) that supplies a stunnel.conf for Exchange Online - setup for on-premise Exchange would be almost identical.
This issue is no longer reproducible in v7.2f. This was not included in any patch release for v7.0.