Email digest with rules

Well, I don't know how to help you on this because your question is so vague. And it's been 5 years, so I doubt you still need an answer. But for the sake of documentation, let me respond:

I have a situation where i will like to send email digest with rules.

Rules has the built-in ability to send plain-text email messages only - because core Drupal only allows you to send email with plain-text and no attachments. If you want to send an email with HTML or with attachments, you must use some other module that extends core Drupal's capability and:

1) Provides support for HTML email and/or attachments.
2) Has support for Rules.

Off the top of my head, that means either the Mime Mail module or the HTML Mail module. There may be others as well.

I have tried subscription module but it doesn't work because i am using domain access and it also has compatibility issues with content access module.

If you want help with your specific situation, you need to provide enough information for us to help you. For instance, "doesn't work" is not helpful at all - what happens? Is there an error? What is the error message? etc. If you have used Rules for this, we need to see an export of your Rule so we can try to reproduce the error and see if it's something you did wrong or if it's a bug in Rules.

Regardless, you don't say anything about the digest - how are you creating it, etc. ? I don't know if the question is about how to create a digest or how to send an attachment, or both. (If it's about how to send an attachment, why did you mentions digests?) I don't know what module you're using to create the digest, whether it supports Rules, where it stores the digest, etc. I don't even know why this is something you want to do with Rules - doesn't your digest module (if there is one) provide a way to send the digests via email? Or are you asking Rules to create the digest for you? I just don't know.

So without complete information, it's really impossible to help you.