Using GMail API in .Net. Creating messaging using Net.Mail.MailMessage. Then using MimeKit to create MimeMessage (using this to send attachment + HTML message). Passing MimeMessage.ToString to Base64 encoder. No API error. Code runs through ok. I can see the message in the sent page in GMail. Mail looks perfect (and the send actually return message id). But then there is the following appended message to this mail in Gmail.
Bounce <[email protected]>
An error occurred. Your message was not sent.
As usual, no other information from Google. How to fix this?
Dim msg = New Net.Mail.MailMessage
msg.Subject = subject
msg.To.Add(New MailAddress(ToEmail))
msg.From = New MailAddress(FromEmail, SenderName)
msg.ReplyTo = New MailAddress(FromEmail, SenderName)
msg.Body = bodyText
msg.IsBodyHtml = True
If Not String.IsNullOrWhiteSpace(fileAttachment) Then
If System.IO.File.Exists(fileAttachment) Then
Dim Attachment As New Net.Mail.Attachment(fileAttachment, "application/pdf")
msg.Attachments.Add(Attachment)
End If
End If
Dim message As MimeMessage = MimeMessage.CreateFromMailMessage(msg)
Dim newMsg = New Google.Apis.Gmail.v1.Data.Message()
newMsg.Raw = Base64UrlEncode(message.ToString)
GmailService.Users.Messages.Send(newMsg, "me").Execute()
Private Function Base64UrlEncode(ByVal input As String) As String
Dim inputBytes = System.Text.Encoding.UTF8.GetBytes(input)
'Special "url-safe" base64 encode.
Return Convert.ToBase64String(inputBytes).Replace("+", "-").Replace("/", "_").Replace("=", "")
End Function
This is the return message. As you can see everything looks ok. Working with Google APIs is the most frustrating thing.
200 OK
- Hide headers -
cache-control: no-cache, no-store, max-age=0, must-revalidate
content-encoding: gzip
content-length: 85
content-type: application/json; charset=UTF-8
date: Sat, 24 Jan 2015 05:57:21 GMT
etag: "96Z6JVARoyR8skov3RseF4DCFpA/mFWFskkdSFxyjIhRJHJuhDCBvfY"
expires: Fri, 01 Jan 1990 00:00:00 GMT
pragma: no-cache
server: GSE
vary: Origin, X-Origin
{
"id": "14b1a841e4fff910",
"threadId": "14b1a841e4fff910",
"labelIds": [
"SENT"
]
}
This is crazy. This was the issue.
This line
msg.ReplyTo = New MailAddress(FromEmail, SenderName)
for whatever reasons (I guess when FromEmail and ReplyTo are same emails) leaves the RFC2822 Reply-To
parameter blank. The parameter remains blank even when msg.ReplyTo
is commented. Needless to say GMail API seems to have issues with Reply-To being left blank. Most definitely a programming bug.
So I had to do this hack in the final RFC2882 message.
inputTxt = Replace(inputTxt, "Reply-To:", "Reply-To: " & FromEmail)
It works now.
********* as pointed out in the comment below, you can use MailMessage.ReplyToList.Add()
instead to solve this issue. So the issue here is that ReplyTo
address is required in Gmail API (even though one might assume that ReplyTo
should default to From
email). **********