I am losing periods in an email sent using Java Mail

Question

I am sending newsletters from a Java server and one of the hyperlinks is arriving missing a period, rendering it useless:

Please print your <a href=3D"http://xxxxxxx.xxx.xx.edu=
au//newsletter2/3/InnovExpoInviteVIP.pdf"> VIP invitation</a> for future re=
ference and check the Innovation Expo website <a href=3D"http://xxxxxxx.xx=
xx.xx.edu.au/2008/"> xxxxxxx.xxxx.xx.edu.au</a> for updates.

In the example above the period was lost between edu and au on the first hyperlink.

We have determined that the mail body is being line wrapped and the wrapping splits the line at the period, and that it is illegal to start a line with a period in an SMTP email:

https://www.rfc-editor.org/rfc/rfc2821#section-4.5.2

My question is this - what settings should I be using to ensure that the wrapping is period friendly and/or not performed in the first place?

UPDATE: After a lot of testing and debugging it turned out that our code was fine - the client's Linux server had shipped with a very old Java version and the old Mail classes were still in one of the lib folders and getting picked up in preference to ours. JDK prior to 1.2 have this bug.

Answer 1

From an SMTP perspective, you can start a line with a period but you have to send two periods instead. If the SMTP client you're using doesn't do this, you may encounter the problem you describe.

It might be worth trying an IP sniffer to see where the problem really is. There are likely at least two separate SMTP transactions involved in sending that email.

Answer 2

I had a similar problem in HTML emails: mysterious missing periods, and in one case a strangely truncated message. JavaMail sends HTML email using the quoted-printable encoding which wraps lines at any point (i.e. not only on whitespace) so that no line exceeds 76 characters. (It uses an '=' at the end of the line as a soft carriage return, so the receiver can reassemble the lines.) This can easily result in a line beginning with a period, which should be doubled. (This is called 'dot-stuffing') If not, the period will be eaten by the receiving SMTP server or worse, if the period is the only character on a line, it will be interpreted by the SMTP server as the end of the message.

I tracked it down to the GNU JavaMail 1.1.2 implementation (aka classpathx javamail). There is no newer version of this implementation and it hasn't been updated for 4 or 5 years. Looking at the source, it partially implements dot-stuffing -- it tries to handle the period on a line by itself case, but there's a bug that prevents even that case from working.

Unfortunately, this was the default implementation on our platform (Centos 5), so I imagine it is also the default on RedHat.

The fix on Centos is to install Sun's (or should I now say Oracle's?) JavaMail implementation (I used 1.4.4), and use the Centos alternatives command to install it in place of the default implementation. (Using alternatives ensures that installing Centos patches won't cause a reversion to the GNU implmentation.)