Glen's Exchange and Office 365 Dev Blog

One of the most basic things you might want to do with EWS is Send a Message, while its may sound easy sending messages programmatically can be at times confusing. But first lets take one step back for a second from EWS and look at the different ways you could send Email programmatically on Exchange. SMTP : (Simple Mail Transfer Protocol) SMTP is the backbone protocol for Email and is how most Email is transferred between servers on the Internet. Its also the protocol POP and IMAP clients use to send email. Because SMTP is a protocol (meaning its a set of rules defined in a RFC) rather then an API  to use it you need to use a library that will give you some objects that you can code against that will then generated the necessary communication that follows the protocol rules. Some example of these are CDOSys, and System.NET.Mail. From an Exchange technical point of view when you submit a message via SMTP your submitting it directly into the Transport Pipeline so it doesn't going

Complex properties are one of the more challenging elements when it comes to developing with Exchange and bitwise properties are one of the more challenging property types you may need to deal with. The most common bitwise property in Exchange you may access/use is the PR_MessageFlags property https://msdn.microsoft.com/en-us/library/ee160304(v=exchg.80).aspx  . If you look at this property on a Message that you received you might see something like What the  ExcludesBitmask SearchFilter/Restriction in EWS allows you to do is create a search where you can specifically exclude messages because they have one of these bitmask values set. Eg you might want to exclude Draft messages from your search or maybe you want to exclude any messages that where SentBy you in the Inbox. You can also use this Search Filter with the Not filter which Negates the restriction so if I created a Searchfilter to excluded all messages with the MSGFlag_HasAttached then negated that with the Not filter I wo