I am currently sending about 400 emails a day using a bespoke program
and Outlook Express as my Email Client. The bespoke program allows the
emails to be sent successively for a single click of a field within
the program, i.e. one click starts the program running and it then
continues until all the emails have been sent. Each email takes about
4 seconds to send and contains about 3 kb of data.

We have had this set-up in place for about 2 years, but over the past
3 months we have started to experience timed-out problems initially to
Yahoo addresses but recently to Hotmail ones.

The emails do not bounce back to us for about 3 or 4 days and then
just say that there was 'congestion' and that the message has been
'timed out'.The 'arrival date' within the bounced message indicates to
us when it was sent.

I wish to know why this is happening and what I need to do to prevent it.

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Clarification of Question by gaga23-ga on 01 May 2004 00:18 PDT

In my comment "with sat quarter of an hour" should say "within sat
quarter of an hour"

Also thought that I would mention that we are using WindowsXP when
sending the emails in question.

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Clarification of Question by gaga23-ga on 01 May 2004 01:05 PDT

Thought it might be useful to add that the daily emails that are sent
have content that is about 95% common.

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Clarification of Question by gaga23-ga on 02 May 2004 14:53 PDT

Whilst accepting that the timed out problems are due to Spam Filters,
it would help me in forming my plan of action if I knew at which
point, in the line of transfer, such filters are rejecting the emails
that we are trying to send. The fact that on one day we get no timed
out messages from Hotmail, but about 80 on the next, when a similar
total number of emails (to a large variety of domain names) was
dispatched by us, suggests to me that the rejection is happening at a
point prior to that where they are trying to enter individual
mailboxes,i.e. at a Hotmail Server at some point down the line of
transfer.

It sounds as if Yahoo and Hotmail spam filters have targeted your
incoming messages.  Many spam filters will simply indicate to the
sender that the message has timed out, rather than provide a "bounce,"
because a bounce helps the spammer to clean up his lists.  By this
technique (a "timed out" message), the spammer does not know for sure
if the address is good or not and this undermines the value of his
address lists.

Query:  are your messages unsolicited, or are you sending to opt-in recipients?

In answer to your query asking if the messages are solicited; they are
being sent to people who have willingly joined our service and we
would expect them to welcome our emails.

With reference to Hotmail, whilst we previously had occasional
timed-out problems with them, today we had about 80 messages rejected
for no apparent reason.

A further complication is that if we are sending several emails to the
same address with say quarter of an hour, some of them will transfer
whilst others will suffer the timed-out fate.

To ipfan, many thanks for your comment,i think it could prove helpful. gaga23

I agree with ipfan's comment regarding the possibility that it is the
spam filters at Yahoo! and Hotmail kicking in due to their sensing an
apparent spam mailing. For your Hotmail recipients. If you wish to
increase the likelihood that your messages will get through, make sure
you are sending them from the same originating address each time, and
ask your Hotmail recipients to add that address to either their
Address List, or their Safe List (if it shows up in their Junk Mail
folder). Best if they add you to their Address List proactively. For
Yahoo! Mail, it's a little different, but the same basic approach
applies - have your recipients add your sending address to their
Address book. Y! Mail does not explicitly have a "Safe Mailers" list
that is editable, but usually if the sending address is in the Address
book, it will get through.

Regards,

aht-ga
Google Answers Researcher

To aht, thanks a lot for your contribution, I feel that I can now make
some progress towards resolving this problem. Best regards, gaga23.