Email attachments

[[email protected]]

We have a problem with one of our clients, they have four machines connected directly to an ADSL router. Only one of these machines is able to send emails with attachments. (Gives an SMTP connection error). Emails without attachements can be sent no problem. We have tried various things, it doesn't seem to matter if we connect via Telkom's or IS's backbone.

Does anyone have any idea what is wrong?

Thanks,
Steven

 

[stoke]

Well - one machine works, so logic dictates that that one machine has something different about it.
Is it using the same email client as the others ?
Is it running WinXP SP1, and the others are on SP2 ?

There should be no difference between sendng attachments, and not sending attachments. But, some email clients use a different port for sending attachmants on that some SMTP servers do accept. (I.E.) Non standard, but faster.

I need some more clues ...

 

[andres101]

please tell me more about these SMTP servers!! I've been thinking about modifying/adding to the SMTP protocol to allow proper binary data...

 

[stoke]

Well - there are proprietory SMTP servers that provide their own way of doing things, and there's the official way of doing things.

The Official RFC is here:
http://ietfreport.isoc.org/idref/rfc3030/

Basically - if the SMTP server you're connecting to says "250-8BITMIME" or "250 CHUNKING" or "250-PIPELINING" or all/combinations of them, after the EHLO, then it supports the binary extention in one of these forms.

So - to use the extention to send 14234 bytes of binary data, the conversation goes (one sidedly) something like this:
EHLO
MAIL FROM:<[email protected]> BODY=BINARYMIME
RCPT TO:<[email protected]>
BDAT 100000
you then send 10000 octets of binary data. This is the default max size.
BDAT 4234
you then send the remaining 4234 octets of binary data.
BDAT 0 LAST
QUIT

Now - email clients and servers that support this protocol are extremely difficult to find, and asking a salesperson a question like that is not really useful at all.

Like I said - that is the official alternative means of sending binary via email, but some clients and servers will utilise their own way of doing it.

A cool SMTP/POP3 learning site is http://www.systemwebmail.com/allfaq.aspx.
Have fun.

 

[DFantom]

Want help, provide the FULL ERROR MESSAGE

 

[[email protected]]

Hi, thanks for all the responses.

Unfortunately we still have this problem.

For SMTP servers, we use the standard servers provided by the ISP for their ADSL clients. We don't think it's a problem with the SMTP servers. We have now also tried connect using an IS account, still the same problem.

Not much help, but here is the error message from Outlook Express:

Your server has unexpectedly terminated the connection. Possible causes for this include server problems, network problems, or a long period of inactivity. Subject 'test', Account: 'mail.webapps.co.za', Server: 'smtp.isdsl.net', Protocol: SMTP, Port: 25, Secure(SSL): No, Socket Error: 10054, Error Number: 0x800CCC0F

 

[DFantom]

Try smtp.saix.net instead