In my earlier post, I had outlined how I filed my income tax return online. After uploading the xml file, I got the pdf file as expected, in my radiosai.org email id which is hosted using Google Apps for Domains. This was from email@example.com and was a zipped pdf file. After mailing it by ordinary post, I got an acknowledgement email after 10 days or so, from firstname.lastname@example.org with a password protected pdf file as an attachment. Unfortunately, the pdf was corrupted, and was not readable using Foxit Reader 3.0 or the latest Adobe Reader. I dashed off an email to email@example.com and they replied asking me to "please contact us at 0124-2438000 or 1800-180-1961 (Toll Free)." Tried calling the tollfree number, they redirected me to the CPC (Centralised Processing Centre), a Bangalore number with 080 STD code. Since the website incometaxindiaefiling.gov.in had a section showing this acknowledgement, I thought perhaps I need not have a copy of the pdf, so I did not follow up.
A month or so later, now, I have received "Intimation U/S 143(1)" from the same firstname.lastname@example.org - again a password protected pdf as an attachment, again corrupted. This time I contacted CPC using their new tollfree number 1800 425 2229. The agent told me that their system had problems with some mail servers, and that yahoo and rediffmail accounts are known to work. He said that if I changed my email on the website at My Account -> Update Phone/Email and then call back after 4 days, they can resend the email. After changing to my rediffmail account, called them back, and this time the password-protected pdf mail attachment opens fine. So they have some issues with the mail server at cpc.gov.in, my guess is that with the digitally signed pdf, something non-standard is happening with the MIME encoding.