I’m creating an outlook message following the sample given here:
This is done on an ASP.NET server page. The created mail is saved server side and presented as link to be downloaded after the creation. This works. After the download Outlook pops up client side with the mail ready to be sent. “To”, “Subject”, “Body” and “Attachment” are already pre-filled, “From” not, because “From” needs to be set by the final sending machine. I’m having an Outlook Automation solution (which I wanted to replace, because it requires an Office installation server side - grrrr), which does exactly that and fine since years.
If I send the mail from my corporate Outlook (MS Exchange behind) MS Exchange sends me a message back: “You are not allowed to send this message, because you are trying to send on behalf of another sender”.
If I send the mail from another machine with a local Outlook installation to my corporate account, the mail drops in on my corporate Outlook as attachment “OriginalMessage.txt” and a body, which tells this
“The content of the attached message is possibly untrustworthy, because the viewable originator-addres may not correspond with the actual originator-address. In the sender’s addres is not a domain included (no @). If this email is needed, contact the sender to change the server address.”
The latter message corresponds to the first, seems to be the same reason. But again - I do not fill the “From” part.
Unfortunately I cannot reproduce that on your demo page, because leaving “From” empty runs into an error.
So I suspect you are pre-setting “From” or any other “From” related field somehow, which clashes with Outlook’s internal knowledge. I also tried to apply the “FROM_ME” flag to no avail.