The dot stuffing bug is a rare issue where a recipient mail server strips a dot from an email.
This is normally not much of a problem if it happens in text but if it happens in a link it can break the link.
The cause of it is down to bug in a recipient's mail server where it does not properly follow the standards for reading an email where the first character on the line is a dot.
The explanation for this is that email standards say that if a dot is the first character on a line then the sending program (that is Vuture in this case) should insert an extra dot at the beginning of the line - and the receiving program (in this case the recipient's mail program) should check to see if the first character is a period and if there are other characters on the line it should delete this period. The reason for all of this is that when the email is encoded to be sent, a dot on its own on a line indicates the end of a message.
This is the section of email standards that explain this: https://tools.ietf.org/html/rfc5321#section-4.5.2
We follow the standards and correctly add an extra dot to the email where required - here is sample extract from our logs:
<h6 style=3D"margin:0;padding:0;font-size:14px;line-height:18px;margin-=
bottom:15px;font-family:Arial, sans-serif;font-weight:normal;color:#000=
001;color:#000001 !important"><strong><a title=3D"Landing Pages/ RSVP -=
Event-Email" href=3D"https://your-company.vuturevx.com/email_handler=
..aspx?sid=3Dblankform&redirect=3Dhttps%3a%2f%2fyour-company.vu=
turevx.com%2f9%2f1328%2flanding-pages%2frsvp---event.asp" styl=
e=3D"-webkit-text-size-adjust:none;color:#6C9DBD;text-decoration:underl=
ine">Click here</a> to RSVP</strong></h6>#
The email_handler.aspx link is split across a line (emails are transmitted with 72 characters per line) and the dot has ended up at the beginning of the line. Email standards say we should add the extra dot which we have done.
An issue at the recipient's end is incorrectly removing both dots from the beginning of the line and breaking the link.
The internet shows examples of the dot stuffing bug occurring with some version of Microsoft Exchange or with some plugins or mail gateways.
It is a hard one to solve without the recipient's messaging team logging a support issue with their mail vendor.
It is a rare occurrence because the link would have to be split with the dot at the beginning of the line which does not happen very often.
