feat: email support using lettre #250

trkelly23 · 2025-03-20T00:02:11Z

This pull request relates #184 email sending functionality using the SMTP protocol. The implementation includes the following key components:

EmailError Enum: Defines various errors that can occur when sending an email, such as message errors, configuration errors, connection errors, and send errors.

SmtpConfig Struct: Represents the configuration for the SMTP email backend. It includes fields for the SMTP server host, port, username, password, fail silently option, and timeout duration. A default implementation is provided.

EmailMessage Struct: Represents an email message with fields for the subject, body, sender email, recipient emails, CC, BCC, reply-to addresses, and alternative parts (e.g., plain text and HTML versions).

EmailBackend Struct: Provides the core functionality for sending emails.

It includes methods to:
Create a new instance with the given configuration.
Open a connection to the SMTP server.
Close the connection to the SMTP server.
Dump the email message to stdout for debugging purposes.
Send a single email message.
Send multiple email messages.
Unit Tests:

Notes
The implementation uses the lettre crate for SMTP transport and message building.
The EmailBackend struct includes a debug flag to enable dumping email messages to stdout for debugging purposes.
The unit tests demonstrate the setup but do not actually send emails, as they mock the transport. In a real test environment, you might use a real SMTP server or a more sophisticated mock.

Future Work
Integration tests with a real SMTP server or a mock server.
Additional configuration options for TLS/SSL support.
Improved error handling and logging.
Integration with API email providers.

Initial commit of email.rs using lettre Initial commit of Add email support using lettre crate Added the message printout if debug mode is enabled Added a test and deferred the extra headers and attachment features. Added tests for config and send_email(ignore).

…/cot into feat-add-email-support

codecov · 2025-03-20T08:47:52Z

Codecov Report

Attention: Patch coverage is 85.81688% with 79 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
cot/src/email.rs	85.81%	57 Missing and 22 partials ⚠️

Flag	Coverage Δ
rust	`81.86% <85.81%> (+0.21%)`	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
cot/src/email.rs	`85.81% <85.81%> (ø)`

... and 3 files with indirect coverage changes

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cot/src/email.rs

seqre

Thank you for your contribution and interest in Cot! I have some questions and made some suggestions for improvement, I'd appreciate it if you acted on them.

Additionally, it'd be great if you could write more tests to ensure sufficient code coverage!

Cargo.toml

cot/src/email.rs

…ded to improve test coverage.

seqre

Great improvement, but there's still some work to do!

cot/src/email.rs

seqre · 2025-03-30T17:21:24Z

cot/src/email.rs

+    /// - `EmailError::ConfigurationError`:
+    ///   - If the SMTP configuration is invalid (e.g., missing required fields like username and password).
+    ///   - If the host is empty or blank in the configuration.
+    ///   - If the credentials cannot be created from the configuration.
+    ///
+    /// - `EmailError::ConnectionError`:
+    ///   - If the transport cannot be created for the specified mode (e.g., invalid host or unsupported configuration).
+    ///   - If the transport fails to connect to the SMTP server.


Please rephrase it as text rather than a bulleted list.

Addressed formatting issues by running and fixing issue found by
cargo +nightly fmt --all -- --check

seqre · 2025-03-30T17:21:53Z

cot/src/email.rs

+    /// - `EmailError::ConfigurationError`:
+    ///   - If the SMTP configuration is invalid (e.g., missing required fields like username and password).
+    ///   - If the host is empty or blank in the configuration.
+    ///   - If the credentials cannot be created from the configuration.
    ///
-    /// # Panics
+    /// - `EmailError::ConnectionError`:
+    ///   - If the transport cannot be created for the specified mode (e.g., invalid host or unsupported configuration).
+    ///   - If the transport fails to connect to the SMTP server.


Addressed formatting issues by running and fixing issue found by
cargo +nightly fmt --all -- --check

seqre · 2025-03-30T17:25:35Z

cot/src/email.rs

+        let transport = if self.config.username.is_some() && self.config.password.is_some() {
+            transport_builder.credentials(credentials).build()
+        } else {
+            transport_builder.build()
+        };


You already did that check above when creating Credentials, no need to duplicate it I think

Suggested change

let transport = if self.config.username.is_some() && self.config.password.is_some() {

transport_builder.credentials(credentials).build()

} else {

transport_builder.build()

};

let transport = transport_builder.credentials(credentials).build();

cot/src/email.rs

m4tx

Overall, this looks fairly good and certainly goes in the right direction! There's still one major issue that needs to be fixed before merging, however.

examples/send-email/src/main.rs

…elp.

trkelly23 · 2025-05-14T02:08:07Z

@seqre I just noticed your comment:
I'm back after a focused effort at work which may have gotten me into a little trouble getting the bootstrapping working with the email configuration. I added the email_backend to the config.rs and project.rs files. However, using it in example/send-email yields no backend initialized.

I think the issue is in project.rs and the bootstrapping timing between WithApps, WithDatabase, and WithEmail.
Could anybody who knows the Project initialization give me any tips or suggestions?

seqre · 2025-05-15T09:36:26Z

Thank you for your patience, @trkelly23! We looked at the code and found out you have just forgotten to call the with_email function that you created. We took the liberty of fixing it and reorganizing slightly to accommodate possible similar additions in the future. We also merged in changes from the newest version, so you don't have to fight with merge conflicts. Now you can continue working on this feature!

As a side note, you might want to install a pre-commit hook, which will ensure your code always follows our formatting standards! Check out our contributing guide for more details!

Additionally, please feel empowered to resolve conversations in PR with comments that you fully applied to the code. Leave open only those where you're unsure or we're actively discussing something. This reduces the amount of work we have to do, thanks!

trkelly23 added 6 commits March 15, 2025 14:12

Initial commit of email.rs using lettre

1d2849e

Initial commit of Add email support using lettre crate

252cebe

Added the message printout if debug mode is enabled

fc1fb9f

Added a test and deferred the extra headers and attachment features.

d64980f

Added tests for config and send_email(ignore).

4edd6d0

Fixed the email example and removed minor version from cargo.

dbbf50f

github-actions bot added the C-lib Crate: cot (main library crate) label Mar 20, 2025

pre-commit-ci bot and others added 4 commits March 20, 2025 00:02

chore(pre-commit.ci): auto fixes from pre-commit hooks

0587340

Merge branch 'feat-add-email-support' of https://github.com/trkelly23…

84eb659

…/cot into feat-add-email-support

chore(pre-commit.ci): auto fixes from pre-commit hooks

c964e45

ElijahAhianyo reviewed Mar 20, 2025

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cot/src/email.rs Outdated Show resolved Hide resolved

trkelly23 and others added 2 commits March 20, 2025 17:08

Implemented a trait impl for the EmailBackend

a13552e

chore(pre-commit.ci): auto fixes from pre-commit hooks

6ac6e92

seqre requested changes Mar 20, 2025

View reviewed changes

trkelly23 and others added 4 commits March 27, 2025 20:57

Refactor to insure multiple email backends could be added. Mocking ad…

d7ac14a

…ded to improve test coverage.

Pushing lock since there seems to be a conflict

4ee5c6a

Merge branch 'master' into feat-add-email-support

49775cd

chore(pre-commit.ci): auto fixes from pre-commit hooks

553c2e9

trkelly23 requested a review from seqre March 28, 2025 14:46

m4tx changed the title ~~(feat): add email support using lettre~~ feat: email support using lettre Mar 30, 2025

seqre requested changes Mar 30, 2025

View reviewed changes

m4tx requested changes Mar 30, 2025

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examples/send-email/src/main.rs Outdated Show resolved Hide resolved

Adding the reworked smtp implementation and NOT working example for h…

cb8093a

…elp.

seqre and others added 4 commits May 15, 2025 10:19

chore: cargo fmt

749ef05

fix bootstrapper

3a042af

chore: merge master

84c111d

chore(pre-commit.ci): auto fixes from pre-commit hooks

ea8e2e0

Merge branch 'master' into feat-add-email-support

fa4f337

Merge branch 'master' into feat-add-email-support

6cc9cb6

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feat: email support using lettre #250

feat: email support using lettre #250

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trkelly23 commented May 14, 2025

seqre commented May 15, 2025

feat: email support using lettre #250

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feat: email support using lettre #250

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