Convert all incoming Plain Text emails to HTML format

New Contributor

Hi everyone and thanks in advance for your help!


We have the need of convert every single incoming email from Plain Text to HTML before delivering to our users; I've been looking for this feature or setting in Office 365 but apparently it is not possible.


The goal is to put a warning HTML banner for the users before getting their messages, so that they can be aware of possible suspected emails.


How we could achieve this?

Thanks again,



2 Replies

There's no supported way to do that. Your options are third-party tools or half-working solution via transport rules. See other workarounds for example here:

Hi @Vasil Michev ,


Thanks for your prompt answer; unfortunally, I'm afraid that article is related to Exchange 2010, instead of Exchange Online, so surely don't apply here.


Anyway, another accepted solution could be adding any particular plain text formatted banner to any incoming message (text box made with characters or something similar); enough to warn the user.


Do you think it could be possible? It could nice if possible to identify which of those comes from HTML or PlainText, so that use different banners


Thanks again,