Random errors appear in alert emails - how could this happen? - php

Question

I'm the webmaster and lead developer for a set of websites providing assessment services. I have no background in server administration and am ashamed to say that being a sysadmin is pretty intimidating to me; I'm comfortable with basic command line, but I'm frequently overwhelmed by all of the myriad configurations needed to get a standard LAMP stack working with several subdomains and an email server running.
I've finally reached something that thoroughly stumps me. Let me first list our basic server configuration:
VPS running Ubuntu 12.04
Standard Apache, PHP, Mysql, BIND services
1 main domain + 4 subdomain websites configured in the above services, two of which make extensive use of mysql databases having 300-400 tables each
Citadel email server (a choice I'm increasingly come to see as a mistake)
Swiftmailer (for sending automated emails from PHP)
Some of our pages (relating to account and assessment management) send alert emails to the test taker, coach, and/or us, when a specific action is taken. The text for these emails is fetched from a "boilerplate" table in the mysql db. Then in PHP, a couple "placeholder" tags are swapped out for test taker name, date, etc. The PHP code then uses Swift Mailer to send the prepared text as an email, with our local Citadel email server, to a given set of (usually external) addresses. We are CC'd on most of these emails, to provide us with a second record of all of the automated messages we've sent.
(Feel free to skip over this) Here's the gist of my code that fetches and processes the text, and sends it as an email:
$subject = $bp['email_report_title'];
$subject = str_replace("[NAME]", $name, $subject);
$subject = str_replace("[INSTRUMENT_NAME]", $instrument_name, $subject);
$body = $bp['email_report'];
$body = str_replace("[NAME]", $name, $body);
$body = str_replace("[INSTRUMENT_NAME]", $instrument_name, $body);
$body = str_replace("[INSTRUMENT_BASE]", $instrument_base, $body);
sendEmail($email_to, $email_from, $email_cc, $subject, $body);
In a nutshell, here's my problem: the emails we see (as a result of the above events) sometimes have typos appear in them -- inconsistently. Here are a couple images as example, showing a set of auto emails generated & sent on the same day using the same PHP code drawing from the same (unaltered) string in our database. These are screenshots from our internal (CC'd) account, viewed in Mac Mail; but based on test taker complaints, all email recipients appear to be seeing the same text. In the first image, note the differences in spacing in the titles.
In the second & third images, note the incorrect link (two periods at the end). I have checked the PHP code and the mysql source text, and can find absolutely no reason that the login link would be changed to have two periods in that spot. EDIT: Based on commenter request, I've copied the full-length email text below the images.
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Lectica, Inc.
Northampton, MA 01060
Our mission is to develop standardized, formative, and diagnostic developmental assessments of the knowledge and skills required to meet the challenges of the 21st century. Our aims are threefold: (1) to build engaging, educative, and feedback-rich developmental assessments and learning resources for K-18 students and their teachers, (2) to create equally rich assessments that diagnose learning needs and support the development of adults (in the workplace and beyond), and (3) to build (and share) knowledge about learning and its role in the future of society.
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Sorry for the long background explanation. But my question is simple: How could these typos happen? At what point in the workflow could a (verified consistent) mysql data cell, fetched and processed by (straightforward) PHP code, plopped into a standard PHP -> SMTP mailer plugin, lead to the creation of an email that appears to have random typos?
I'd love any ideas you have, and I'm glad to provide more detailed code if needed. Thanks in advance.
EDIT: Thanks to Eggyal for pointing out that only the longer subject lines have the spaces removed. This pattern holds true across other older emails too. Also, I've provided the full text of one email alert above; note the '..php' at the end of the link. All emails have the same signature line, and all alert emails of the same type have the same length body (plus or minus 15 characters for different instrument names and test taker names).

Answer 1

I have experienced very similar behavior in emails when using plain php's mail() function and postfix smtp server. It took me weeks to figure it out why HTML in those emails is randomly corrupted: it was long lines in the email source, exactly as #eggyal writes in the comments.
RFC2822 states that lines should be no more than 78 chars. To comply, SMTP server inserts newlines at selected places, however this can easily corrupt space-sensitive content. Check the Content-Transfer-Encoding header in your emails, I assume it will be either 7bit, 8bit or quoted printable.
Try changing it to base64 - that's the easy way. I'm not familiar with Swift Mailer but I guess this could work:
$transferEncoding = $message->getHeaders()->get('Content-Transfer-Encoding');
$transferEncoding->setValue('base64');
Alternatively, you can try to wrap lines manually before handing over to SMTP server.