The originating email program and particularly the full source listing of the (assumed) SMTP mail message as submitted on OpenVMS is of interest, as are details of the particular gateway(s) involved -- some of the gateways into the Microsoft Exchange environment can be (mis)configured to do exactly this sort of message line break.
Try this with a couple of target gateways, too, to try to narrow this to OpenVMS and the sending program, or to the (assumed) Microsoft Exchange gateway.
It's also feasible that whatever program is generating the message or submitting it into SMTP on OpenVMS is chopping it.
"Are there any known issues with outlook breaking up website addresses?"
FWIW, Microsoft products are not the central area of expertise of this particular ITRC forum; this isn't the best forum for Microsoft questions. Do consider checking the Microsoft knowledge base or the Microsoft ITRC forum -- if there is one -- for details on and questions concerning Microsoft products.
Do consider reviewing what text gets submitted into the mail system to see if it is getting stomped before the gateway, check the gateway itself, and do take a look at the raw message within both the Microsoft client and within another available client connected into the Exchange server (assuming the Exchange Server is configured to permit non-Microsoft access). Evolution with the Exchange connector may be an option here, if the configuration does not permit non-Microsoft clients.
