When you are composing an email you can select which attachments you want to add to the mail. Congressus has set limits to the size and data usage of these files.

Why are there limits?

When you are sending files via email you are using data traffic. Congressus has to pay for this datatraffing. When you, as an association are sending a large file to all your members, you will use a lot of data traffic. This is because every message including attachments is send independently. When you send a file of 1MB to a 1000 members you are using roughly 1 x 1000 = 1 GB of data traffic.

We want to prevent that a lot of data traffic will cause us to have increase the prices of the services we offer. That is why we have set limits to the sending of attachments via mailing.

Maximum file size

At the moment the maximum size of attachment files in emails is 1 MB*. Also the total size of all attachments cannot exceed more than 1 MB.

Data usage per month

In addition to the file size we also evaluate the total data usage of mailings you send. The data usage is dependant on the file size of the attachment times the total amount of receivers of the mailing. A file of 1MB send to 250 recipients uses a total 250MB of data

As a customer you get a data limit per calendar month. This data limit is based on the total amount of members list on your last invoice from Congressus. This way we ensure every customer gets a proportionate amount.


For every invoiced member an association gets 1 MB of data per month *. If your associations paid for 1200 member on their last invoice, then in the next calendar month you get 1200 MB of data.

We show the available date in the current month when you compose your emails. In the case you compose an email with attachments which would go over your limits then you will be unable send the email. In that case there are alternative possibilities of sending files to your members

*We evaluate the data usage of all our customers and on that basis we will decide if the limits will be adjusted in the future.


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