Generally the suggestion is to use a 3rd party service to send out the mail on your behalf. Normally these services will have a good track record with the Yahoos, Hotmails and Gmails of the world. The added benefit is that you keep your domain name off any blacklists.

one way to deal with yahoo mail (and hotmail) is to disallow registration from those accounts, as this forum does.
as bill mentioned, the established email list management services can make it work.
this WebmasterWorld search for yahoo email problems [google.com] will convince you it has been a common problem for a long time.

There are a number of factors that can affect newsletter rejection.

A handful of things that I have come across:

1. Do not use a webmail account as your "from" address
2. Do not send a newsletter that is just an embedded image
3. Do not use multiple fonts or point sizes
4. Plain text is always good.
5. Use a "good neigbourhood" to send from. I cut rejection rates by switching from my ISPs SMTP server to that of the company managing my domain name.

one way to deal with yahoo mail (and hotmail) is to disallow registration from those accounts, as this forum does.

How will you make sure that the mails are coming from the above mentionned sources?

Are they always formed the same?

Which kind of filter do you use? Regex?

one way to deal with yahoo mail (and hotmail) is to disallow registration from those accounts, as this forum does.

5. Use a "good neigbourhood" to send from. I cut rejection rates by switching from my ISPs SMTP server to that of the company managing my domain name.

These two solutions seem to be the most effective.
I will try them.

Another thing to bear in mind is that part of Yahoo's spam filtering is driven by users clicking on the "This is Spam" button. Be very careful to send only to those of your users who have explicitly opted-in to mailings, and be very careful to avoid sending them e-mail too often.

In this latter case, they may simply hit the "This is Spam" button, rather than taking the trouble to follow your "unsubscribe" procedure. Or they may do it if your unsubscribe procedure is not obvious, does not work, or does not take immediate effect. Most may do it because they don't understand the difference, but some may do it out of spite.

I almost did this myself last week, but caught myself at the very last second. With the economic situation as it is, even major corporations have upped their marketing message frequency -- some to a point that is quite annoying; I don't need daily updates from companies that I order from only once or twice a year!

Jim

Keep the list clean. Log all bounces and if anything bounces twice the drop that address.