postmark is a haskell toolkit for dealing with the postmarkapp.com api for sending and receiving email.

postmarkHttp "<your api token>"   -- Build PostmarkSettings to talk to
                                  -- the _http_ api with you own api token.
postmarkHttps "<your api token>"  -- Build PostmarkSettings to talk to
                                  -- the _https_ api with you own api token.
postmarkHttpTest                  -- Build PostmarkSettings to talk to
                                  -- the _http_ api with the public test token.
postmarkHttpsTest                 -- Build PostmarkSettings to talk to
                                  -- the _https_ api with the public test token.

Sending a single email.

import Network.Api.Postmark

request postmarkHttpTest $ email defaultEmail {
      emailFrom = "demo-from@postmark.hs"
    , emailTo = ["demo-to@postmark.hs"]
    , emailSubject = "demo, yes it really is a demo"
    , emailTag = Just "demo"
    , emailHtml = Just "Hello world!"
    , emailReplyTo = "demo-reply-to@postmark.hs"
    }

Sending multiple emails.

import Network.Api.Postmark

demo = request postmarkHttpTest $ emails [
    defaultEmail {
      emailFrom = "demo-from@postmark.hs"
    , emailTo = ["demo-to@postmark.hs"]
    , emailSubject = "demo, yes it really is a demo"
    , emailTag = Just "demo"
    , emailHtml = Just "Hello world!"
    , emailReplyTo = "demo-reply-to@postmark.hs"
    }
  , defaultEmail {
      emailFrom = "demo-from@postmark.hs"
    , emailTo = ["demo-to@postmark.hs"]
    , emailSubject = "demo, yes it really is a demo"
    , emailTag = Just "demo"
    , emailHtml = Just "Hello world again!"
    , emailReplyTo = "demo-reply-to@postmark.hs"
    }
  }

Checking if the response is a success, ignoring detail:

import Network.Api.Postmark

case result of
  PostmarkSuccess _ -> True

Handling specific failure cases:

import Network.Api.Postmark

case result of
  PostmarkSuccess a ->  undefined            -- Everything ok.
  PostmarkUnauthorized -> undefined          -- Invalid api token.
  PostmarkFailure (PostmarkError errortype message)
                    -> undefined             -- A standard postmark failure.
  PostmarkUnexpected reason code body message
                    -> undefined             -- Unexpected failure (bug or
                                             -- api change).

Handling known postmark failures:

import Network.Api.Postmark

case errortype of
  PostmarkBadApiToken -> undefined
  PostmarkInvalidEmail -> undefined
  PostmarkSenderNotFound -> undefined
  PostmarkSenderNotConfirmed -> undefined
  PostmarkInvalidJson -> undefined
  PostmarkIncompatibleJson -> undefined
  PostmarkNotAllowed -> undefined
  PostmarkInactive -> undefined
  PostmarkBounceNotFound -> undefined
  PostmarkBounceQueryException -> undefined
  PostmarkJsonRequired -> undefined
  PostmarkTooManyMessages -> undefined
  PostmarkUnkownError Int -> undefined