There should be no need to specifically detach the data source. Having
executed the one merge, close the mailmerge main document.
You can also add an envelope to the main documnet and insert the merge
fields in the appropriate places and then just execute one merge. That's
not much use however unless your printer can handle it.

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Hope this helps,
Doug Robbins - Word MVP
> Is it possible to create a mail merge of letters and
> envelopes at the same time. Or does it need to be done
> separately. Merge the letters 1st then detach data source
> and mege envelopes.
>
> Thanks