[dsl]

Maybe the standards documents you are used to differ from RFCs, but here is the official language:

   3. SHOULD   This word, or the adjective "RECOMMENDED", mean that there
      may exist valid reasons in particular circumstances to ignore a
      particular item, but the full implications must be understood and
      carefully weighed before choosing a different course.

SHOULD is effectively REQUIRED unless it conflicts with another standards requirement or you have a very specific edge case.

[jcelerier]

I just don't understand how you get from the text you pasted to "required". Nowhere does it say that anything is effectively required. Words have meaning.

[nerdsniper]

> the full implications must be understood and carefully weighed before choosing a different course.

In this case, the full implication is that your email might be undeliverable. "Should" indicates that the consequences for this fall on the entity that is deviating from the thing they "should" be doing.

[vel0city]

You should wear sunscreen to the beach. Its recommended as a good way to prevent sunburn. However, the beach police aren't going to come get you for not wearing it. You just might get a sunburn if you don't plan accordingly with other sun countermeasures.

[ForHackernews]

"there may exist valid reasons in particular circumstances" means effectively required in my common sense understanding of American English.

[BeetleB]

Nope, it's exactly what it says: RECOMMENDED.

Any time any document (standards or otherwise) says something is recommended, then of course you should think it through before going against the recommendation. Going from their verbiage to:

> SHOULD is effectively REQUIRED unless it conflicts with another standards requirement or you have a very specific edge case.

is a fairly big leap.

[azernik]

"The full implications must be understood and carefully weighed before choosing a different course." (emphasis mine)

i.e. you are required to have a good reason not to do it.

[HDThoreaun]

This very clearly says that SHOULD is not effectively REQUIRED at all, and is fact nothing more than RECOMMENDED. Really not sure how you misinterpreted this so badly

[allarm]

You should read it again.

[sigseg1v]

It's not required but they need to understand the implications. In this case the implication is that Google drops the mail. So clearly they didn't understand the implications.

[andoando]

required means it must exist, not that it may or may not exist depending on the reason