Outlook 2013 sends plain text with attachment mail as uuencoded with SMTP conn

[sisrahul]

Hi,

Looks like there is an issue with Outlook 2013 client. I've noticed that if plain text email is sent with an attachment with SMTP connection then outlook lose the MIME format and sends uuencoded message to exchange server. I believe Outlook/Exchange server still supports the uuencoding so we don't see any problem when the message reaches to recipients but this is creating issues in our outlook add-in. Since our add-in expects that outlook should send MIME message. Outlook shows this peculiar behavior only in case of Plain text email with attachment and SMTP connection. If I repeat the same scenario with same attachment in Outlook 2010, I don't see any issue. Outlook 2010 sends proper MIME message.

I've collected the raw logs (attached with this thread) of DATA command in case of Outlook 2010 x86 and outlook 2013 x86, which clearly shows the difference. I am trying to send "first.png" attachment in plain test.

I am trying to understand why does outlook 2013 shows this peculiar behavior . Is this a bug or OL2k13 is trying to follow some standard, if yes what standard ?

 

[Diane Poremsky]

Re: Outlook 2013 sends plain text with attachment mail as uuencoded with SMTP

uuencoding is triggered when the number of 'special' characters exceeds some number - i don't recall if it's a fixed # or a % of text, but I asked about it when my newsletter kept getting converted to uuencoding. 'Special' characters would be any non-alphanumeric number I believe, but again, i forget the exact details. I'll see if i can find the email.

From looking at your logs, it looks like there is only an attachment, so uuencoding shouldn't kick in.

I'll see what i can find out about it.

 

[sisrahul]

Re: Outlook 2013 sends plain text with attachment mail as uuencoded with SMTP

uuencoding is triggered when the number of 'special' characters exceeds some number - i don't recall if it's a fixed # or a % of text, but I asked about it when my newsletter kept getting converted to uuencoding. 'Special' characters would be any non-alphanumeric number I believe, but again, i forget the exact details. I'll see if i can find the email.

From looking at your logs, it looks like there is only an attachment, so uuencoding shouldn't kick in.

I'll see what i can find out about it.

Thanks Diane for quick reply. Yes, there is only one attachment of fairly little size 253 byte. I don't see any special characters in email as email is written English with only text in mail body "PT from OL13". Moreover this happens with only OL2K13 not with OL2k10 so I've a strong feeling that it is a bug. Looking forward to see your response.