Skip to main content

It is important to understand the entire mail flow from sender to receiver. It helps to understand the entire mechanics and workings of all the several components that exists in the mail flow topology. The understanding of this will help you to troubleshoot why some email cannot be send or why you cannot receive certain emails.

A - User compose a  email using Mail Client. The email is sent from mail client to mail server via SMTP, MAPI or ActiveSync. The Mailbox maintain constant connectivity
B - Mail Server check for outgoing mail security rules/policies
C - If YES, then check for Internal Mailbox
D - Deliver to Mailboxes
E - If uncached or new MX Domain record, then query MX from DNS Server
F - Sender Mail to Receiver Mail Server via SMTP (25, 2525) or SMTPS (465) or SMTP/TLS (587)
G - Received Mail Server check SPF records
H - Mail Server check for incoming mail security rules/policies
I - Mail Server check for valid user mailbox
J - Mail Server deliver to User mailbox
K - Mail Client maintain constant connectivity between Mail Client and User Mailbox
L - Mail Client check for incoming mail security rules/policies

SMTP (Simple Mail Transfer Protocol) is a communication protocol for electronic mail transmission. As an Internet standard, SMTP was first defined in 1982 by RFC 821, and updated in 2008 by RFC 5321 to Extended SMTP additions, which is the protocol variety in widespread use today. Mail servers and other message transfer agents use SMTP to send and receive mail messages. Proprietary systems such as Microsoft Exchange and IBM Notes and webmail systems such as Outlook.com, Gmail and Yahoo! Mail may use non-standard protocols internally, but all use SMTP when sending to or receiving email from outside their own systems. SMTP servers commonly use the Transmission Control Protocol on port number 25.

SMTPS (Simple Mail Transfer Protocol Secure) is a method for securing the SMTP using transport layer security. It is intended to provide authentication of the communication partners, as well as data integrity and confidentiality.
SMTPS is not a proprietary protocol and not an extension of SMTP. It is a way to secure SMTP at the transport layer, by wrapping SMTP inside TLS. Conceptually, it is similar to how HTTPS wraps HTTP inside TLS.




Comments

Post a Comment

Popular posts from this blog

New  Microsoft 365 " The world’s productivity cloud " this represents the vision for the future of Microsoft. It is an integrated set of apps and services that puts artificial intelligence (AI) and other cutting-edge innovations to work for you. At a moment when businesses are facing extraordinary health and economic challenges. Why are you making these changes? Microsoft 365 is an integrated set of apps and services that puts AI and other cutting-edge innovations to work for you. And for small and medium-sized businesses, that includes new capabilities in Microsoft Teams to help you host rich meetings and events online; cloud file storage and sharing capabilities so you can collaborate from anywhere; and security and identity solutions to safeguard your businesses. Second, we’re always looking for ways to simplify. This new approach to naming our products is designed to help you quickly find the plan you need and get back to your business. How does Office fit into Microsoft...
Post a Comment
Read more
As the world adjusts to remote working, Microsoft CEO Satya Nadella and product marketing manager Aya Tange discuss the new capabilities in Microsoft Teams making it easier for teams to communicate and collaborate. New Microsoft Teams features include the ability to turn on live capti ons, as well as the ability to raise a hand in meetings to ensure all voices are heard. Certainly, that will help in the engagement of the participants. Another great feature is the ability to suppress background noise. Discover how new Microsoft Teams features can help make the most of work from home productivity: https://msft.it/6002Tc8p8 Subscribe to Microsoft 365 on YouTube here: https://aka.ms/SubscribeToM365 Follow us on social: LinkedIn: https://www.linkedin.com/showcase/mic... Twitter: https://twitter.com/Microsoft365 Instagram: https://www.instagram.com/microsoft365/ Facebook: https://www.facebook.com/Microsoft365/ IT Support, IT Company, IT Services Win-Pro Singapore IT Support, IT Comp...
Post a Comment
Read more