Mail Merge does not interpolate variables in the Body field of emails after updating to Thunderbird 78.8.0 for accounts with End-to-End Encryption enabled

[fabacab]

I have been using Mail Merge for a long time and greatly appreciate the work you put into this Add-On for Thunderbird.

Recently, after updating to Thunderbird 78.8.0, I am no longer able to use Mail Merge because while variables are interpolated successfully in the email headers (like the Subject and To fields), variables in the Body of an email are not getting interpolated. This only happens on email accounts whose Account Settings have End-to-End Encryption enabled (OpenPGP, in my case).

I can work around the issue by setting the affected accounts to use the "None" setting when selecting an OpenPGP key, and leaving the S/MIME public certificate field blank.

Prior to updating to Thunderbird 78.8.0 earlier this week (that version of Thunderbird was first released on February 23, 2021), Mail Merge was able to successfuly interpolate variables in the Body field of an email message even when an OpenPGP key was enabled and selected for that account. To be more precise, before updating to Thunderbird 78.8.0, I was able to send unencrypted/plaintext emails through Mail Merge as expected, but after updating Thunderbird to that version, Mail Merge is only able to replace {{Variables}} in email headers (like the To) field, not the Body of that message.

This makes Mail Merge far less useful because in order to use it, I have to first open the Account Settings window, disable OpenPGP support for the given account identity, and then use Mail Merge.

[fabacab]

This recent Mozilla Thunderbird Add-Ons Review for Mail Merge could be related, as it describes a similar (or the same?) issue.

[siefkenj]

Can you check if this is still an issue in version 2.4? https://addons.thunderbird.net/en-US/thunderbird/addon/mail-merge-p/?src=search

[siefkenj]

MailMergeP now only works with TB >= 91, so I am closing this issue for now.