Unexpected expection thrown when testing the email settings with an invalid email

[MikeAlhayek]

Describe the bug

When testing the email settings with an invalid email format, the SmtpService display the following error

An error occurred while sending an email: 'Unexpected 'A' token at offset 5'

To Reproduce

Steps to reproduce the behavior:

1. Enable OC.Email feature
2. Click on Configuration >> Settings >> Email
3. Make sure the email settings is configured. then click on "Test settings" button
4. Provide invalid formatted email address in the "sender" field.
5. Provide "To" email, "Subject" and "Body" and click send.

Expected behavior

A clear and concise description of what you expected to happen.

Screenshots

If applicable, add screenshots to help explain your problem.

[hishamco]

Before I dig into this PR, while I worked a lot in this area, I'm suggesting to replace your PR with the one introduced in #11130 /cc @sebastienros your thought, because we already supported localization for data annotations

[MikeAlhayek]

Not sure that I understand Hisham. The referenced PR seems to be doing something completely different. PR #12253 fixes missing validation in the SmtpService.

[hishamco]

My PR handles both the validation and localization in data annotations attributes, so what we need here is something like EmailAddressAttribute which is handle the validation that you are trying to do using IValidatableObject

So, no need to introduce such kind of validation because we already supported localization in data annotations level

[MikeAlhayek]

@hishamco you may want to review that PR.

[hishamco]

You could review if you can, also I'm asking @sebastienros and @agriffard to review it if it's possible