Example in the README doesn't work

Operating System (Linux/Mac/Windows/iOS/Android): Linux 5.12.1
Delta Chat Version:
- for the bot (sender): this very library, last tag released (0.0.1)
- for the client (receiver): 1.14.5
Expected behavior: the example in the readme works after providing valid email/psw credentials and a valid receiver (i.e. I receive and hello world message)

Actual behavior: I have the following behavior when launching the example:

λ go run ./test.go 
2021/05/10 22:09:55 Configuring
2021/05/10 22:09:55 src/sql.rs:1448: [migration] v72
2021/05/10 22:09:55 src/sql.rs:1460: [migration] v73
2021/05/10 22:09:55 src/sql.rs:1541: Opened "stuff.db".
2021/05/10 22:09:55 src/sql.rs:1417: [migration] v69
2021/05/10 22:09:55 src/sql.rs:758: First time init: creating tables in "stuff.db".
2021/05/10 22:09:55 src/sql.rs:1431: [migration] v71
2021/05/10 22:09:55 src/configure/mod.rs:85: Configure ...
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:55 src/configure/mod.rs:525: Trying: imap: <redacted>:993 security=SSL certificate_checks=automatic oauth2=false
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:55 src/configure/mod.rs:554: Trying: smtp: <redacted>:587 security=SSL certificate_checks=automatic oauth2=false
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_NEW_BLOB_FILE
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_MSGS_CHANGED
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_NEW_BLOB_FILE
2021/05/10 22:09:55 src/configure/mod.rs:560: failure: SMTP: failed to connect: io: error:1408F10B:SSL routines:ssl3_get_record:wrong version number:ssl/record/ssl3_record.c:331:
2021/05/10 22:09:55 src/configure/mod.rs:554: Trying: smtp: <redacted>:587 security=STARTTLS certificate_checks=automatic oauth2=false
2021/05/10 22:09:55 src/contact.rs:501: added contact id=10 addr=<redacted>
2021/05/10 22:09:55 Got unhandled event: DC_EVENT_CONTACTS_CHANGED
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_MSGS_CHANGED
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_NEW_BLOB_FILE
2021/05/10 22:09:56 src/chat.rs:1548: Attaching "stuff.db-blobs/welcome-image-1374773839.jpg" for message type #Image.
2021/05/10 22:09:56 src/configure/mod.rs:537: success: imap: <redacted>:993 security=SSL certificate_checks=automatic oauth2=false
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_MSGS_CHANGED
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_MSGS_CHANGED
Enter text: 2021/05/10 22:09:56 Got unhandled event: DC_EVENT_MSGS_CHANGED
2021/05/10 22:09:56 src/configure/mod.rs:566: success: smtp: <redacted>:587 security=STARTTLS certificate_checks=automatic oauth2=false
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_SMTP_CONNECTED
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_MSGS_CHANGED
2021/05/10 22:09:56 Sent hello world message!
2021/05/10 22:09:56 DC_EVENT_ERROR: Failed to send text message: Cannot prepare message for sending, address is not configured.
2021/05/10 22:09:56 src/imap/mod.rs:1298: Scanning folder: Name { response: ResponseData { raw: 4096, response: MailboxData(List { flags: ["\\HasNoChildren", "\\UnMarked"], delimiter: Some("."), name: "DeltaChat" }) }, inner: InnerName { attributes: [Custom("\\HasNoChildren"), Custom("\\UnMarked")], delimiter: Some("."), name: "DeltaChat" } }
2021/05/10 22:09:56 src/imap/mod.rs:1298: Scanning folder: Name { response: ResponseData { raw: 4096, response: MailboxData(List { flags: ["\\HasNoChildren", "\\UnMarked", "\\Drafts"], delimiter: Some("."), name: "Drafts" }) }, inner: InnerName { attributes: [Custom("\\HasNoChildren"), Custom("\\UnMarked"), Custom("\\Drafts")], delimiter: Some("."), name: "Drafts" } }
2021/05/10 22:09:56 src/imap/mod.rs:1298: Scanning folder: Name { response: ResponseData { raw: 4096, response: MailboxData(List { flags: ["\\HasNoChildren", "\\UnMarked", "\\Sent"], delimiter: Some("."), name: "Sent" }) }, inner: InnerName { attributes: [Custom("\\HasNoChildren"), Custom("\\UnMarked"), Custom("\\Sent")], delimiter: Some("."), name: "Sent" } }
2021/05/10 22:09:56 src/imap/mod.rs:1298: Scanning folder: Name { response: ResponseData { raw: 4096, response: MailboxData(List { flags: ["\\HasNoChildren", "\\UnMarked", "\\Junk"], delimiter: Some("."), name: "Junk" }) }, inner: InnerName { attributes: [Custom("\\HasNoChildren"), Custom("\\UnMarked"), Custom("\\Junk")], delimiter: Some("."), name: "Junk" } }
2021/05/10 22:09:56 src/imap/mod.rs:1298: Scanning folder: Name { response: ResponseData { raw: 4096, response: MailboxData(List { flags: ["\\HasNoChildren", "\\UnMarked", "\\Trash"], delimiter: Some("."), name: "Trash" }) }, inner: InnerName { attributes: [Custom("\\HasNoChildren"), Custom("\\UnMarked"), Custom("\\Trash")], delimiter: Some("."), name: "Trash" } }
2021/05/10 22:09:56 src/imap/mod.rs:1335: Using "." as folder-delimiter.
2021/05/10 22:09:56 src/imap/mod.rs:1298: Scanning folder: Name { response: ResponseData { raw: 4096, response: MailboxData(List { flags: ["\\HasNoChildren"], delimiter: Some("."), name: "INBOX" }) }, inner: InnerName { attributes: [Custom("\\HasNoChildren")], delimiter: Some("."), name: "INBOX" } }
2021/05/10 22:09:56 src/imap/mod.rs:1336: sentbox folder is Some("Sent")
2021/05/10 22:09:56 src/imap/mod.rs:1399: FINISHED configuring IMAP-folders.
2021/05/10 22:09:56 src/imap/mod.rs:624: uid/validity change folder INBOX: new 13/1603398574 previous 0/0
2021/05/10 22:09:56 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:57 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:57 src/key.rs:253: Generating keypair with type Default
2021/05/10 22:09:57 src/key.rs:258: Keypair generated in 0s.
2021/05/10 22:09:57 src/configure/mod.rs:422: key generation completed
2021/05/10 22:09:57 src/job.rs:198: saving job for Imap-thread: Job { job_id: 0, action: FetchExistingMsgs, foreign_id: 0, desired_timestamp: 1620677397, added_timestamp: 1620677397, tries: 0, param: Params { inner: {} }, pending_error: None }
2021/05/10 22:09:57 src/job.rs:1215: interrupt: imap
2021/05/10 22:09:57 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS
2021/05/10 22:09:57 Got unhandled event: DC_EVENT_CONFIGURE_PROGRESS

In particular the following line 2021/05/10 22:09:56 DC_EVENT_ERROR: Failed to send text message: Cannot prepare message for sending, address is not configured.

Steps to reproduce the problem: I have copy-pasted the example, changed the addr variable to a valid email address (on the same server instance the bot is running), set the bot credentials (credentials that work if used on delta-chat Android application). The mail server hosting the emails is the following: https://github.com/docker-mailserver/docker-mailserver, last version (9.1).
Screenshots: N/A
Logs: see above

As last note, I use this email server with delta chat for Android and Desktop without problems. I copy-pasted the configuration from the desktop and used a brand new account for the bot.

deltachat / go-deltachat

Example in the README doesn't work #2