Email errors are quite confusing.
“550 5.4.1 Relay Access Denied” is one such error you see in Office 365 servers.
Here, you know that something is not proper as you see “Access Denied” in the error, but not sure where’s the problem.
At Bobcares, we often resolve such email errors as part of our Technical Support Services for web hosting companies.
Microsoft Exchange Servers enforce strict restrictions on Email sending limits (30 emails per minute) to prevent spam and to keep accounts safe.
If your account exceeds this limit, you may get blocked by your Exchange server.
“550, 5.1.8, Access Denied, Bad outbound sender” is one such issue reported by Office 365 users.
At Bobcares, we often resolve such Exchange email errors as a part of our Technical Support Services for web hosting companies.