subjectContains not triggering when there is more text in subject

[PetherPettersson]

I am trying to get a build to trigger when we receive an email notifying the team of a new software release. The problem is that the 'subjectContains' trigger will not trigger on this release subject which contains platform, release name, version, etc. But it will if I remove every other text but 'release' and leave some release numbering, or add whitespace.

I'm using just parts of the subject in this issue as it shows the problem.

Steps to reproduce

How can we reproduce the issue

1. subjectContains=release
2. Receive email with a0.01release in subject
3. Email will not trigger build when polling

Expected behaviour

Build will trigger.

Actual behaviour

Build will not trigger.

Server configuration

Operating system:
ubuntu-17.10.1

Jenkins Version:
Jenkins ver. 2.89.4

Plugin Version:
1.026

Mail Server:
imap.gmail.com

Additional Steps/Questions

'Testing Connection' with four unread emails.
Email : 0.01release
Email: 0.01release(
Email: a0.01release
Email: a0.01 release

All but the 'a0.01release' is found.

Connecting to the mailbox...
Found properties:

• [attachments:IGNORE]

• [folder:INBOX]

• [host:imap.gmail.com]

• [mail.debug:false]

• [mail.debug.auth:false]

• [mail.imaps.host:imap.gmail.com]

• [mail.imaps.port:993]

• [password:***]

• [receivedXMinutesAgo:1440]

• [storeName:imaps]

• [subjectContains:release]

• [username:***]
  Connected to mailbox. Searching for messages where:

• [flag is unread]

• [subject contains 'release']

• [received date is greater than '2018/03/18 15:12:41 PM']
  ...
  Searching folder...
  Found matching email(s) : 3

• 0.01release (2018/03/19 14:57:22 PM)

• 0.01release( (2018/03/19 15:04:01 PM)

• a0.01 release (2018/03/19 15:12:24 PM)
  'Test connection' mode enabled - server connection skipped

Result: Success!