I use Outlook 2013 quite often to send text messages to a mobile phone through my Exchange 2013 server. I've just noticed that the messages are all getting cut off at around 150 characters. I am thinking this is a setting on my phone (Gingerbread OS) although cannot find any setting that would affect this. I have heard others tell me that they are not receiving complete texts from me. I have tested by sending an email-to-text to my phone and if the message is too long it gets cut off.
I did some more testing. When sending a text from my Outlook to my phone, the text itself does come through completely, however when the text is converted back to email, the email is where it gets cut off. In the sent items there is the full email shown (on both Outlook and phone). So I went to compose another test text from Outlook and discovered that the first "Message 1" is the only one that comes through (which is only part of the full message). The extra characters are moved automatically to a new message which shows in the preview of the composition window (i.e. Message 2, Message 3, and so on), this happens in the composition window although on the receiving end only the first "Message" comes through.