Email attachment gets corrupted when sending using SMTP server

[New User]

Hi,

I have a PDF file that I am trying to send as an attachment through a C#
program. Even though the PDF file can be opened by itself, sometimes the
same
file cannot be opened as an attachment. If I try and open the original PDF
file I have no problems.

I have used System.Web.Mail .MailMessage to create an
email and an SMTPMail object to send the mail.
I tried to change the encoding to Base64 but even that has not helped. There
are still ocassions when I am unable to open the attachment.

Has anybody experienced this problem or do you have any suggestions .

Thanks!!

[Jon Skeet [C# MVP]]

New User <Ne*****@discus sions.microsoft .com> wrote:

I have a PDF file that I am trying to send as an attachment through a C#
program. Even though the PDF file can be opened by itself, sometimes the
same
file cannot be opened as an attachment. If I try and open the original PDF
file I have no problems.

I have used System.Web.Mail .MailMessage to create an
email and an SMTPMail object to send the mail.
I tried to change the encoding to Base64 but even that has not helped. There
are still ocassions when I am unable to open the attachment.

Has anybody experienced this problem or do you have any suggestions .

Could you post a short but complete program which demonstrates the
problem?

See http://www.pobox.com/~skeet/csharp/complete.html for details of
what I mean by that.

--
Jon Skeet - <sk***@pobox.co m>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[Jacky Kwok]

New User wrote:

Hi,

I have a PDF file that I am trying to send as an attachment through a C#
program. Even though the PDF file can be opened by itself, sometimes the
same
file cannot be opened as an attachment. If I try and open the original PDF
file I have no problems.

I have used System.Web.Mail .MailMessage to create an
email and an SMTPMail object to send the mail.
I tried to change the encoding to Base64 but even that has not helped. There
are still ocassions when I am unable to open the attachment.

Has anybody experienced this problem or do you have any suggestions .

Thanks!!

In my experience, sometimes the "System.Web.Mai l" will use a incorrect
attachment encoding even you had set it to "Base64". It seems the
problem is related to some version of "CDO" object installed in the
system by other application(e.g . MS office).
I solve the problem to force the encoding by changing the mail header.
MailMessage message = new MailMessage();
....
MailAttachment attach;
attach = new MailAttachment( file,MailEncodi ng.Base64);
message.Attachm ents.Add(attach );
....
//-> add this line
message.Headers .Add("Content-Transfer-Encoding","base 64");
....

--
Jacky Kwok
jacky@alumni_DO T_cuhk_DOT_edu_ DOT_hk
jacky@compose_D OT_com_DOT_hk