Send multiple email attachments to multiple recipients.
I think that most of us know that you can
use the SNDDST command to send an email with a single attachment. But what do
you do if you need to send multiple attachments? Or send to multiple persons?
Well, you have a few options. First, you can take the easy way out and just send
multiple emails with a single attachment (no shame in that...I did it for
years). Or you can take the bull by the horns and use the QTMMSENDMAIL API to
send multiple attachments to multiple people in a single email. Although getting
started using QTMMSENDMAIL will require some work up front, the returns are well
worth the effort. But there are several items to be addressed (no pun intended)
before using the API.
First, you need to create a MIME-formatted email
file and place it in the IFS. In my opinion, this is the most difficult part of
using the QTMMSENDMAIL API. IBM apparently figures that if you are using the
API, then you must be able to recite RFC822 from memory, because IBM has no
documentation regarding building a MIME email file. For those of you who are
unfamiliar with RFC822, it is the
document that defines the "standard for the format of ARPA Internet text
messages." Feel free to wade through it at your leisure. It is not an easy read,
but it does have some good information. Personally, I would not bother with it
unless you are planning to build your own version of Outlook or Eudora. I found
an excellent "how-to" article
that was much more helpful. In addition, I have included a sample of a valid
MIME-formatted email below. If you are only going to be sending text messages
and text files (flat text or comma delimited), you can just use the sample I
have included as a guide. If you are planning to email programs or *SAVF types
of files, you will probably need to get detailed information from the sources
mentioned above.
Once you understand how to create your MIME email file,
you can move on to the next hurdle. To send email using QTMMSENDMAIL, you need
to call it with the correct parameters. However, in this instance, that is not
as simple as it sounds. To start with, the IBM documentation is not clear on how
to format the parameters. To make matters worse, those of us who are
predominantly RPG programmers are used to working with fixed field lengths and
tend to be thrown off by variable field lengths and pointers.
If you
are familiar with C and/or C++ and the use of structures, you can probably skip
the next few paragraphs. For the rest of you, I will walk you through the
process so you get a thorough understanding of how to build the structure(s)
needed for the QTMMSENDMAIL API.
The QTMMSENDMAIL API has seven
required parameters:
- File Name is the IFS path and file name of
the MIME email file. Maximum file name length is 255.
- File Name Length is the length of the file name. Max is 255.
- Originator Address is the email address of the sender. Maximum
originator address length is 256.
- Length of Originator is the length of the originator address. Max is
256.
- Recipient Structure is the data structure (ADDTO100) of all
recipients. Maximum length for any single recipient address is 256.
- Total Number of Recipients should be obvious. It's the total number
of persons the email is being sent to, including carbon copies (CC) and blind
carbon copies (BCC).
- Error Code is the standard API error structure. See the IBM
documentation for details.
The tricky part is that the file
name, originator address, recipient structure, and error code are passed as
pointers, and the recipient structure occurs once for each recipient. Passing
pointers is simply a matter of using the %ADDR BIF to get the address of each of
the fields. The multiple occurrences of the recipient structure (ADDTO100) need
to be placed end to end into a large field or data structure. In the sample
program, I use a function to prepare each occurrence and then append it to the
large RecipTbl field. This process of appending each occurrence could be further
shortcut by using a pointer and moving the data directly into the RecipTbl field
(alas, I have a deadline, so I'm not going back to change it now).
Gotchas
There are a few things to watch for when using
QTMMSENDMAIL. Foremost among these is that if your MIME email file is incorrect
in some way, the API will complete successfully (i.e., QUSEC shows no error),
but the email(s) never show up at the destination. This was an irritating
problem when I was learning to create the MIME emails correctly. As a side note,
the originator and recipients listed in the MIME file do not necessarily have to
match the ones you send as parms to the QTMMSENDMAIL API. However, this causes
some unexpected results (as I found out) and is not recommended.
Also,
the conversion between EBCDIC and ASCII can be a problem. If everything you are
sending is binary data (e.g., programs, *SAVF files, etc.), you will not have
this problem. However, if you are sending data from a file as an attachment, you
will need to convert the data to ASCII.
Lastly, I have not included any
error checking on the API call in the sample
program. You may want to add some (just in
case).
Jeff Olen is a member of the AS/400
development team at Gauss Interprise, a content management software company
located in Irvine, California. He can be reached by email at
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