{"id":1765,"date":"2017-09-13T04:37:00","date_gmt":"2017-09-13T04:37:00","guid":{"rendered":"https:\/\/www.gmass.co\/blog\/?p=1765"},"modified":"2017-09-13T04:37:00","modified_gmt":"2018-07-11T06:34:34","slug":"upgrading-mimekit-broke-our-email-address-parser","status":"publish","type":"post","link":"https:\/\/www.gmass.co\/blog\/upgrading-mimekit-broke-our-email-address-parser\/","title":{"rendered":"Upgrading MimeKit broke our email address parser"},"content":{"rendered":"

This article is intended for software developers or those interested in the code behind GMass.<\/em><\/p>\n

GMass is written mostly in C#<\/strong> and JavaScript<\/strong>, and the C# backend makes heavy use of a popular email parsing component called MimeKit<\/a>. In face, MimeKit, has become so popular that Microsoft is now recommending that developers use it as the standard<\/a> instead of Microsoft’s own\u00a0SmtpClient library.<\/p>\n

Over the weekend, we updated some of the software components that GMass is built on in preparation for a big feature launch, and in doing so, we updated MimeKit from version 1.12 to the latest release 1.18<\/strong>. That upgrade unfortunately broke some of our email address validation code, and many users\u00a0saw a “token offset”\u00a0error as a result.<\/p>\n

Here’s what happened. Previously, in version 1.12, the following scenarios would pass without throwing an exception:<\/p>\n

\"MimeKit<\/a>
MimeKit Code Sample: These scenarios pass, and no exception is thrown.<\/figcaption><\/figure>\n

After updating to version 1.18, the\u00a0top two of the three scenarios do throw an exception:<\/p>\n

\"MimeKit<\/a>
MimeKit Code Sample: After updating to version 1.18, these throw a parsing exception.<\/figcaption><\/figure>\n

The impact on GMass is such that if you’re connecting to a Google Sheets spreadsheet, and your column containing email addresses has a bad data value\u00a0that is an invalid email address, such as “test@test.com;test@test.com”, whereas before our code would handle this appropriately and eventually filter the bad entry out, now all of a sudden, our code was throwing an exception.<\/p>\n

Making matters more complex was that the MimeKit TryParse<\/strong> didn’t always catch a string that could not be converted into a MimeKit.MailboxAddress<\/strong> object. For example:<\/p>\n

\"MimeKit<\/a>
MimeKit Code Sample: TryParse returns true, but the string still can’t be converted to a MailboxAddress object.<\/figcaption><\/figure>\n

In the above samples, TryParse<\/strong> returns false<\/strong> for “test@test.com;test@test.com” but returns true<\/strong> for “test<test@test.com>”. It returns true<\/strong> for the latter because it assumes that the part outside the angle brackets is the Name<\/strong>, and so Name=test<\/strong> and Address=test@test.com<\/strong>. Our code though attempts to create a MailboxAddress<\/strong> object\u00a0from the whole string, and in this case, the parse into Name<\/strong> and Address<\/strong> doesn’t happen, as the constructor assumes that the entire string represents just the Address<\/strong> portion of the object.<\/p>\n

We did check the\u00a0Release Notes for MimeKit<\/a> before deploying the update, but there was nothing indicating the change in email parsing rules. Still however, we are eternally grateful to Jeffrey Stedfast<\/strong><\/a> for building and maintaining the MimeKit<\/strong> library for the .NET framework. Without it, my job as a software developer parsing and assembling email messages would be far more difficult.<\/p>\n

 <\/p>\n","protected":false},"excerpt":{"rendered":"

This article is intended for software developers or those interested in the code behind GMass. GMass is written mostly in C# and JavaScript, and the C# backend makes\u2026<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[4260,26],"tags":[],"class_list":["post-1765","post","type-post","status-publish","format-standard","hentry","category-bugs","category-gmass"],"acf":[],"yoast_head":"\r\nUpgrading MimeKit broke our email address parser<\/title>\r\n<meta name=\"description\" content=\"GMass is written in C# and JavaScript and makes heavy use of a C# component called MimeKit. 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