I recently had a paper accepted by a journal. When I looked it up on the AMS’ *[Mathematical Reviews](https://mathscinet.ams.org/mathscinet/index.html)*, I noticed that it was previously indexed by the service but, at present, is it not. The journal is not pay-for-play, and one of the previous editors was a very famous mathematician.


I asked the handling editor about this and this person informed me that the journal could not “ensure regular periodicity over the year”. This person also informed me that the journal was removed by zbMATH.


My questions:


1. What possible reasons are there that a journal is removed by an indexing service?
2. Is it necessarily a sign of (lack of) quality that a journal is removed by an indexing service?



Journal losing indexing services
To answer the first question: There are three main reasons why a journal would be removed from indexing lists, at least these are the three used for the [Impact Factor list:](https://clarivate.com/essays/journal-selection-process/)


*A journal may be removed if it encourages self-citation (e.g. if authors are strongly suggested to cite 5 articles recently published in this journal or if such a suggestion is made to increase the impact factor of other journals belonging to the same publisher), if its quality goes down (e.g. if its behavior will start resembling 'pay and we'll publish whatever stuff you'll send us' journals) or if it does not manage to publish new volumes regularly.*


The last point, which seems to apply to the OP, is explained in more detail as follows:


*A journal must be publishing according to its stated frequency to be considered for indexing. The ability to publish on time implies a healthy backlog of manuscripts essential for ongoing viability. It is not acceptable for a journal to appear chronically late, weeks or months after its cover date.*


So, to answer the second question -- no: a journal that publishes irregularly may removed from indexing even if its quality is not compromised.


