Access Exchange Mail Server

In the course of developing an application for a client, I had to access to a Mail inbox with a software via any of the several Servers: IMAP, Exchange, POP3. After hours/days of trying, not a single server was able to access the Mail inbox- the odd was that each time I pinged the server, It was reachable, the credentials were correct and the outlook web access was also working well.
1 answer

When explaining the highly technical problem such as this, one really must specify all the integrating parts, including the versions of each and every libraries in use. This seems to me as one of those problems that are so simple, that overthinking prevents you from solving it. Have you perhaps tried reaching out to .NET community online (you must know stackoverflow)? But before posting there, read this :). If that doesn't help, I have some friends who are .NET gurus and will be more then wiling to help :)
Also, I must denote, days and days of such agony were my usual weekly routine when I started working as a junior dev.