diff --git a/docs/content/a-mail-server's-101.md b/docs/content/a-mail-server's-101.md
index acfd97e1..9e721dcb 100644
--- a/docs/content/a-mail-server's-101.md
+++ b/docs/content/a-mail-server's-101.md
@@ -125,7 +125,7 @@ My MTA will thus have to support two kinds of Submission:
                     ┌────────────────────┐                    ┌┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┐
 Me ---------------> ┤                    ├ -----------------> ┊                 ┊
                     │       My MTA       │                    ┊ Third-party MTA ┊
-Me <--------------- ┤                    ├ <----------------- ┊                 ┊
+                    │                    ├ <----------------- ┊                 ┊
                     └────────────────────┘                    └┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┘
                                ┗━━━━━━━━━━ Inward Submission ━━━━━━━━━━┛
 ```
@@ -162,6 +162,18 @@ Granted it's still very difficult enforcing encryption between MTAs (Transfer/Re
 - It does not enable Explicit TLS (STARTTLS) on port 25 by default. One may enable it through advanced custom configuration, either as a replacement (bad!) or as a supplementary mean of secure Inward Submission.
 - One may also secure Inward Submission using advanced encryption scheme, such as DANE/DNSSEC and/or MTA-STS.
 
+Overall, `docker-mailserver`'s default configuration for SMTP looks like this:
+
+```txt
+ ┏━━━━ Outward Submission ━━━━┓
+                    ┌────────────────────┐                    ┌┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┐
+Me -- cleartext --> ┤(25)            (25)├ --- cleartext ---> ┊                 ┊
+Me -- STARTTLS ---> ┤(587)  My MTA       │                    ┊ Third-party MTA ┊
+                    │                (25)├ <---cleartext ---- ┊                 ┊
+                    └────────────────────┘                    └┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┄┘
+                               ┗━━━━━━━━━━ Inward Submission ━━━━━━━━━━┛
+```
+
 ### Retrieval - IMAP
 
 A MUA willing to fetch an email from a mail server will most likely communicate with its [IMAP](https://en.wikipedia.org/wiki/IMAP) server. As with SMTP described earlier, communication will take place in the form of data packets exchanged over a network that both the client and the server are connected to. The IMAP protocol makes the server capable of handling _Retrieval_.