Within your Onpipeline account you will be able to write an email from anywhere you see an email address. Just click on it to open the email client.
All emails sent to contacts or received from an email you have in the CRM will be automatically connected to the proper contacts or open deals linked to that contact. The connection is not in real time and depends on the email sync. In other words your email first pass through your mail server and then it will be read again by Onpipeline to find the connection. Please remember that if -for example- your “Sent Mail” folder is not synced, you will not see that email until you move it to a synced folder.
Attachment limit is 2 GB. Other limits may depend on your email provider.