When building up your source library, you may come across situations in which a publisher has both a RSS feed and an email subscription available. So, which source should you add?
This will completely depend on the publisher, which feeds/emails you are looking at, and which source you prefer to use. We usually recommend using RSS feeds over all other formats, including Email2Linex, when possible, as those are less likely to need updates than if an email stops matching a rule or the format changes, etc. in which case this will have to be caught by an organisation administrator and then updated or reported to us depending on the change. Items to consider when both a RSS feed and an email subscription are available are: content populating each source, format, and timeliness.
Some publishers may provide additional content in an email subscription that they don't provide in their RSS feed (or vice versa), especially if the email is a paid subscription but they have a public RSS available. In other cases the email and the RSS are the same, in which case you will want to look at the other two factors below.
One of the decisions you make when converting an email to a source is to determine how that email will be converted. Sometimes the email itself will determine that if, for instance, it has attachments, or is one article in the body of the email and doesn't have links to content. In other cases, it may be that your users would prefer to have 1 link per email to be viewed in a browser, rather than having the individual articles parsed out. With an RSS you will always get each content item individually. Additionally Email2Linex is often used when some subscribers want to receive the original email format (as an E2L forwarding alert) and others want the email combined in their Shared or Personal Alert (as a source).
If the content in both are the same and the delivery format is the same, then the timeliness of updates is the final item to review. Some publishers send out a delivery of all emails very early in the morning and then the RSS is updated later. Sometimes this is reversed. This will affect when the content populates Linex and therefore your alerts. While RSS feeds are being crawled every few hours, email sources are only updated when a new email is received, but at that point are immediately available in Linex, rather than waiting for the next crawl.
In cases where alerts are going out once a day or once a week this last point less critical and, if all else above is the same, it comes down to your preference.